435 



py 1 



STANDARD METHODS OF TESTING 
AND SPECIFICATIONS FOR CEMENT 



CONTENTS 

United States Government Specification for Portland 
Cement. 

Standard Specifications for Cement of the American 
Society for Testing Materials. 

Methods for Testing Cement — Report of the Committee 
of the American Society of Civil Engineers. 

Chemical Analyses. 



ASSOCIATION OF AMERICAN 
PORTUND CEMENT MANUFACTURERS 

BELLEVUE COURT BUILDING, PHILADELPHIA. PA. 



STANDARD METHODS OF TESTING 
AND SPECIFICATIONS FOR CEMENT 



CONTENTS 

United States Government Specification for Portland 
Cement. 

Standard Specifications for Cement of the American 
Society for Testing Materials. 

Methods for Testing Cement — Report of the Committee 
of the American Society of Civil Engineers. 

Chemical Analyses. 



Y c^vtjc^X'Vv-cl C.>g,^^VV>jg,yt^\^ CXxL^<;Mri^^ C:^lo-(^^^.q 

ASSOCIATION OF AMERICAN 
PORTLAND CEMENT MANUFACTURERS 

BELLEVUE COURT BUILDING, PHIUDELPHIA, PA. 



u 



n UNITED STATES GOVERNMENT SPECIFICATION FOR 
r PORTLAND CEMENT 



^ ■ 

^ CONTENTS 

EXECUTIVE ORDER 4 

INTRODUCTORY STATEMENT 5 

I. SPECIFICATION 

1. Definition 6 

2. Composition 6 

3. Specific gravity 6 

4. Fineness 6 

5. Soundness 6 

6. Time of setting 6 

7-10. Tensile strength 7 

II. Brand 7 

12-13. Packages 7 

14-15. Inspection 7 

Standard Methods of Testing 

16-17. Sampling 8 

18-19. Chemical analysis . 8 

20-21. Determination of specific gravity 9 

22-23. Determination of fineness 9 

24. Mixing cement pastes and mortars 10 

25-28. Determination of normal consistency 10 

29. Determination of soundness 11 

30. Determination of time of setting 11 

3 1 . Tensile tests 11 

32. Storage of test pieces 12 

33~35- Standard sand 12 

II. METHODS OF CHEMICAL ANALYSIS 

Prefatory note 12 

Chemical Analysis 

Solution 13 

Silica 13 

Alumina and iron 14 

Iron 14 

Lime 15 

Magnesia 15 

Alkalies 16 

Sulphuric anhydride acid 17 

Total sulphur 17 

Loss on ignition 18 

Insoluble residue 18 

III. INTERPRETATION OF RESULTS 

Chemical 18 

Physical 

Specific gravity 20 

Fineness 21 

Normal consistency 21 

Mixing 23 

Soundness 23 

Time of setting 23 

Tensile tests 24 

IV. AUXILIARY SPECIFICATIONS 

Bureau of Standards sieve specifications 25 

Bureau of Standards specification for specific-gravity flasks 27 

Standard form of briquettes 29 

3 



EXECUTIVE ORDER 

It is hereby ordered that all Portland cement that may hereafter 
be purchased by any Department, Bureau, Office, or independent 
establishment of the Government, or that may be used in construc- 
tion work connected with any of the aforesaid branches of the 
Government service, shall conform in every respect to the speci- 
fication for Portland cement adopted by the Departmental Con- 
ference at the meeting held at the Bureau of Standards on February 
13, 1912, and approved by the heads of the several departments (to 
be known as the United States Government Specification for Port- 
land Cement) : Provided, however, that such specification may be 
modified from time to time by any similar Departmental conference, 
with the approval of the heads of the several Departments. 

Wm. H. Taft. 
The White House, 

April 30, 1 91 2. 



't 




INTRODUCTORY STATEMENT 

In June, 191 1, the Secretary of the Department of Commerce 
and Labor arranged, through the Secretaries of the various de- 
partments, for a conference of Government engineers for the purpose 
of unifying the specifications for Portland cement used by the 
United States Government. At this conference a committee was 
appointed to consider existing specifications and to recommend 
a single specification for Portland cement to be used by all depart- 
ments of the Government. 

After an extended series of meetings of this committee, at which 
careful consideration was given to representative specifications for 
Portland cement, as well as to all available data on methods of tests, 
a tentative specification was developed, which was reported to the 
departmental conference at a general meeting held July 20, 191 1. 

In view of the desirability of agreement between the specifica- 
tions in use by the public and those adopted by the Government, 
the committee was instructed by the conference to confer with 
representative consumers and manufacturers as well as the special 
committees of the national engineering societies more directly 
interested in the subject of cement specifications. As a result the 
tentative specifications first reported by the departmental com- 
mittee were modified slightly, until substantial agreement was 
reached on practically all points except the methods of determining 
the normal consistency and time of setting, and the following speci- 
fications were unanimously adopted by the departmental conference 
at the meeting held February 13, 1912. 

It was recognized that no specification can be considered final, 
but must be subject to revision from time to time as occasion re- 
quires, and provision will be made for such revision by the various 
Government departments, all of which have adopted the specifica- 
tion as recommended by the conference. 

S. W. Stratton, 

Director. 
Approved : 

Charles Nagel, 

Secretary. 



UNITED STATES GOVERNMENT SPECIFICATION FOR 
PORTLAND CEMENT* 



I. SPECIFICATION 

Definition. — i. The cement shall be the product obtained by 
finely pulverizing clinker produced by calcining to incipient fusion, 
an intimate mixture of properly proportioned argillaceous and 
calcareous substances, with only such additions subsequent to 
calcining as may be necessary to control certain properties. Such 
additions shall not exceed 3 per cent, by weight, of the calcined 
product. 

Composition. — 2. In the finished cement, the following limits 
shall not be exceeded : 

Per cent 

Loss on ignition for 15 minutes 4 

Insoluble residue . I 

Sulphuric anhydride (SO3) 1.75 

Magnesia (MgO) 4 

Specific Gravity. — 3. The specific gravity of the cement shall 
be not less than 3.10. Should the cement as received fall below this 
requirement, a second test may be made upon a sample heated for 
30 minutes at a very dull red heat. 

Fineness. — 4. Ninety-two per cent of the cement, by weight, 
shall pass through the No. 100 sieve, and 75 per cent shall pass 
through the No. 200 sieve. 

Soundness. — 5. Pats of neat cement prepared and treated as 
hereinafter prescribed shall remain firm and hard and show no sign 
of distortion, checking, cracking, or disintegrating. If the cement 
fails to meet the prescribed steaming test, the cement may be re- 
jected or the steaming test repeated after seven or more days at 
the option of the engineer. 

Time of Setting. — 6. The cement shall not acquire its initial 
set in less than 45 minutes and must have acquired its final set 
within 10 hours. 

* Circular No. 33, Bureau of Standards, May i, 1912. 
6 



I 
4 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

Tensile Strength. — 7. Briquettes made of neat cement, after 
being kept in moist air for 24 hours and the rest of the time in water, 
shall develop tensile strength per square inch as follows: 

Pounds 

After 7 days 500 

After 28 days 600 

8. Briquettes made up of i part cement and 3 parts standard 
Ottawa sand, by weight, shall develop tensile strength per square 
inch as follows : 

Pounds 

After 7 days 200 

After 28 days 275 

9. The average of the tensile strengths developed at each age 
by the briquettes in any set made from one sample is to be con- 
sidered the strength of the sample at that age, excluding any results 
that are manifestly faulty. 

10. The average strength of the sand mortar briquettes at 28 
days shall show an increase over the average strength at 7 days. 

Brand. — 11. Bids for furnishing cement or for doing work in 
which cement is to be used shall state the brand of cement proposed 
to be furnished and the mill at which made. The right is reserved 
to reject any cement which has not established itself as a high-grade 
Portland cement, and has not been made by the same mill for two 
years and given satisfaction in use for at least one year under 
climatic and other conditions at least equal in severity to those of 
the work proposed. 

Packages. — 12. The cement shall be delivered in sacks, barrels, 
or other suitable packages (to be specified by the engineer), and 
shall be dry and free from lumps. Each package shall be plainly 
labeled with the name of the brand and of the manufacturer. 

13. A sack of cement shall contain 94 pounds net. A barrel 
shall contain 376 pounds net. Any package that is short weight 
or broken or that contains damaged cement may be rejected, or 
accepted as a fractional package, at the option of the engineer. 

Inspection. — 14. The cement shall be tested in accordance with 
the standard methods hereinafter prescribed. In general the 
cement will be inspected and tested after delivery, but partial or 
complete inspection at the mill may be called for in the specifications 
or contract. Tests may be made to determine the chemical com- 
position, specific gravity, fineness, soundness, time of setting, 
and tensile strength, and a cement may be rejected in case it 

7 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

falls to meet any of the specified requirements. An agent of the 
contractor may be present at the making of the tests or they may 
be repeated in his presence. 

15. In case of the failure of any of the tests, and if the contractor 
so desires, the engineer may, if he deem it to the interest of the 
United States, have any or all of the tests made or repeated by the 
Bureau of Standards, United States Department of Commerce 
and Labor, in the manner hereinafter specified, all expenses of such 
tests to be paid by the contractor. All such tests shall be made on 
samples furnished by the engineer. 



Standard Methods of Testing 

Sampling. — 16. The selection of the samples for testing will be 
left to the engineer. The number of packages sampled and the 
quantity to be taken from each package will depend on the im- 
portance of the work, the number of tests to be made, and the 
facilities for making them. 

17. The samples should be so taken as to represent fairly the 
material, and, where conditions permit, at least i barrel in every 
50 should be sampled. Before tests are made samples shall be 
passed through a sieve having 20 meshes per linear inch to remove 
foreign material. Samples shall be tested separately for physical 
qualities, but for chemical analysis mixed samples may be used. 
Every sample should be tested for soundness, but the number of 
tests for other qualities will be left to the discretion of the engineer. 

Chemical Analysis. — 18. The method to be followed for the 
analysis of cement shall be that proposed by the Committee on 
Uniformity in the Analysis of Materials for the Portland Cement 
Industry, reported in the Journal of the Society for Chemical 
Industry, volume 21, page 12, 1902, and published in Engineering 
News, volume 50, page 60, 1903, and in the Engineering Record, 
volume 48, page 49, 1903. 

19. The insoluble residue shall be determined on a i-gram 
sample, which is digested on the steam bath in hydrochloric acid 
of approximately 1.035 specific gravity until the cement is dissolved. 
The residue is filtered, washed with hot water, and the filter-paper 
contents digested on the steam bath in a 5 per cent solution of 
sodium carbonate. The residue is then filtered, washed with hot 
water, then with hot hydrochloric acid, approximately of 1.035 
specific gravity, and finally with hot water, then ignited and 
weighed. The quantity so obtained is the insoluble residue. 

8 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

Determination of Specific Gravity. — 20. The determination of 
specific gravity may be made with a standardized apparatus of 
Le ChateHer or other equally accurate form. Benzine (62° Baume 
naphtha), or kerosene free from water should be used in making 
the determination. The cement should be allowed to pass slowly 
into the liquid of the volumenometer, taking care that the powder 
does not adhere to the sides of the graduated tube above the liquid 
and that the funnel through which it is introduced does not touch 
the liquid. The temperature of the liquid in the flask should not 
vary more than 1° F. during the operation. To this end the flask 
should be immersed in water. The results of repeated tests should 
agree within o.oi. 

21. If the specific gravity of the cement as received is less than 
3.10, a redetermination may be made as follows: 

Seventy grams of the cement is placed in a nickel or platinum 
crucible about 2 inches in diameter and heated for 30 minutes at a 
temperature between 419° C. and 630° C. After the cement has 
cooled to atmospheric temperature the specific gravity shall be de- 
termined in the same manner as described above. The cement 
should be heated in a muffle or other suitable furnace, the temper- 
ature of which is to be maintained above the melting point of zinc 
(419° C.) but below the melting point of antimony (630° C). This 
maximum temperature can be recognized as a very dull red which is 
just discernible in the dark. 

Determination of Fineness. — 22. The No. 100 and No. 200 
sieves shall conform to the standard sieve specifications of the 
Bureau of Standards, Department of Commerce and Labor. 

23. The determination of fineness should be made on a 50-gram 
sample, which may be dried at a temperature of 100° C. (212° F.) 
prior to sifting. The coarsely screened sample should be weighed 
and placed on the No. 200 sieve, which, with the pan and cover 
attached, should be held in one hand in a slightly inclined position 
and moved forward and backward in the plane of inclination, at 
the same time striking the side gently about 200 times per minute 
against the palm of the other hand on the upstroke. The operation 
is to be continued until not more than 0.05 gram will pass through 
in one minute. The residue should be weighed, then placed on the 
No. 100 sieve, and the operation repeated. The sieves should be 
thoroughly dry and clean. Determination of fineness may be made 
by washing the cement through the sieve or by a mechanical sifting 
device which has been previously standardized with the results 
obtained by hand sifting on equivalent samples. In case of the 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

failure of the cement to pass the fineness requirements by the wash- 
ing method or the mechanical device, it shall be tested by hand. 

Mixing Cement Pastes and Mortars. — 24. The quantity of 
cement or cement and sand to be used in the paste or mortar should 
be expressed in grams and the quantity of water in cubic centi- 
meters. The material should be weighed, placed upon a non-ab- 
sorbent surface, thoroughly mixed dry if sand be used, and a crater 
formed in the center, into which the proper percentage of clean 
water should be poured : the material on the outer edge should be 
turned into the crater by the aid of a trowel. As soon as the water 
has been absorbed the operation should be completed by vigorously 
mixing with the hands for one minute and a half. During the opera- 
tion of mixing, the hands should be protected by rubber gloves. 
The temperature of the room and the mixing water should be main- 
tained as nearly as practicable at 21° C. (70° F.). 

Determination of Normal Consistency. — 25. The normal con- 
sistency for neat paste to be used in making briquettes and pats 
should be determined by the ball method, as follows: 

26. A quantity of cement paste should be mixed in the manner 
above described under Mixing Cement Pastes and Mortars, and 
quickly formed into a ball above 2 inches in diameter. The ball 
should then be dropped upon a hard, smooth, and flat surface from 
a height of 2 feet. The paste is of normal consistency when the 
ball does not crack and does not flatten more than one-half of its 
original diameter. 

27. Trial pastes should be made with varying percentages of 
water until the correct consistency is obtained. 

28. The percentage of water to be used in mixing mortars for 
sand briquettes is given by the formula : 

^ = ^^ +K 

in which y is the percentage of water required for the sand mortar, 
P is the percentage of water required for neat cement paste of 

normal consistency, 
n is the number of parts of sand to one of cement by weight, and 
i^ is a constant which for standard Ottawa sand has the value 6.5. 

The percentage of water to be used for mortars containing 3 
parts standard Ottawa sand, by weight, to i of cement is indicated 
in the following statement : 



10 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

Percentage of water for Percentage of water for i to 3 mortars 

neat cement paste of standard Ottawa sand 

18 9.5 

19 9-7 

20 9.8 

21 .... lO.O 

22 10.2 

23 10.3 

24 ^o-5 

25 10.7 

26 10.8 

27 II. o 

28 II. 2 

29 11.3 

Determination of Soundness. — 29. Pats of neat cement paste 
of normal consistency about 3 inches in diameter, one-half inch in 
thickness at the eenter, and tapering to a thin edge, should be kept 
in moist air for a period of 24 hours. One pat should then be kept 
in air and a second in water, at the ordinary temperature of the 
laboratory not to vary greatly from 21° C. (70° F.), and both ob- 
served at intervals for at least 28 days. A third pat should be 
exposed to steam at atmospheric pressure above boiling water for 
5 hours. 

Determination of Time of Setting. — 30. The time of setting 
should be determined by the standardized Gillmore needles, as 
follows: A pat of neat cement paste about 3 inches in diameter 
and one-half inch in thickness with fiat top, mixed at normal con- 
sistency, should be kept in moist air, at a temperature maintained 
as nearly as practicable at 21° C. (70° F.). The cement is con- 
sidered to have acquired its initial set when the pat will bear, with- 
out appreciable indentation, a needle one-twelfth of an inch in 
diameter loaded to weigh one-fourth of a pound. The final set 
has been acquired when the pat will bear, without appreciable 
indentation, a needle one twenty-fourth of an inch in diameter, 
loaded to weigh i pound. In making the test the needle should be 
held in a vertical position and applied lightly to the surface of the 
pat. The pats made for the soundness test may be used to de- 
termine the time of setting. 

Tensile Tests. — 31. Tensile tests should be made on an approved 
machine. The test pieces shall be briquettes of the form recom- 
mended by the Committee on Uniform Tests of Cement of the 
American Society of Civil Engineers, and illustrated in Circular 33 
of the Bureau of Standards. The briquettes shall be made of paste 
or mortar of normal consistency. Immediately after mixing, the 
paste or mortar should be placed in the molds, pressed in firmly 
by the fingers and smoothed off with a trowel without mechanical 

11 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

ramming. The material should be heaped above the mold, and in 
smoothing off, the trowel should be drawn over the mold in such a 
manner as to exert a moderate pressure on the material. The 
molds should be turned over and the operation of heaping and 
smoothing off repeated. Not less than three briquettes should be 
made and tested for each sample for each period of test. The 
neat tests are not considered so important as the sand tests. The 
briquettes should be broken as soon as they are removed from the 
water. The load should be applied at the rate of 600 pounds per 
minute. 

Storage of Test Pieces. — 32. During the first 24 hours after 
molding the test pieces should be kept in air sufficiently moist to 
prevent them from drying. After 24 hours in rnoist air the test 
pieces should be immersed in water. The air and water should be 
maintained as nearly as practicable at 21° C. (70° F.). 

Standard Sand. — 33. The sand to be used shall be natural sand 
from Ottawa, 111., screened to pass a No. 20 sieve and retained on a 
No. 30 sieve. 

34. Sand having passed the No. 20 sieve shall be considered 
standard when not more than 2 grams pass the No. 30 sieve after 
one minute continuous sifting of a 200-gram sample. 

35. The No. 20 and No. 30 sieves shall conform to the standard 
sieve specifications of the Bureau of Standards, Department of 
Commerce and Labor. 



II. METHODS OF CHEMICAL ANALYSIS 
Prefatory Note. — While it may not be necessary to follow the 
standard method of analysis in routine tests when only a general 
indication of composition is desired, this method, including all 
precautions as stated in footnotes and italicized text, must always 
be followed when the results are to be used as the basis for rejection, 
or when an accurate knowledge of composition is desired. 

The standard method can only yield accurate results in the 
hands of a careful and experienced analyst when all precautions 
are properly observed and even under these conditions the results 
obtained in the determinations of magnesia (MgO), sulphuric 
anhydride (SO3), ''loss on ignition" and "insoluble residue" may 
be =*= o.io per cent in error, while in general results reported for 
magnesia tend to be too high. Under less favorable conditions 
the errors may be of much greater magnitude. 

12 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

It is desired to emphasize these points so as to prevent rejection 
of material if the specified limits are exceeded by less than o.io 
per cent. 

Chemical Analysis 

METHOD SUGGESTED FOR THE ANALYSIS OF LIMESTONES, RAW MIXTURES, 
AND PORTLAND CEMENT BY THE COMMITTEE ON UNIFORMITY IN TECH- 
NICAL ANALYSIS WITH THE ADVICE OF W. F. HILLEBR.AND 

Report of Siihcommittee {New York Section Society of Chemical Industry) on Uniformity in Analy- 
sis of Material for the Portland Cement Industry^ 

{All matter printed in italics, both in text and footnotes, has been added during 
the preparation of this circular at the suggestion and with the approval of W. F. Hille- 
brand, with special application to the analysis of Portland Cement.) 

Solution. — One-half gram- of the finely powdered substance 
is to be weighed out and, if a limestone or unburned mixture, 
strongly ignited in a covered platinum crucible over a strong blast 
for 15 minutes, or longer if the blast is not powerful enough to effect 
complete conversion to a cement in this time. It is then transferred 
to an evaporating dish, preferably of platinum for the sake of 
celerity in evaporation, moistened with enough water to prevent 
lumping, and 5 to 10 c.c. of strong HCl added and digested with the 
aid of gentle heat and agitation until solution is completed. Solution 
may be aided by light pressure with the flattened end of a glass 
rod.^ The solution is then evaporated to dryness, as far as this 
may be possible on the bath. 

Silica (Si02). — The residue without further heating is treated 
at first with 5 to 10 c.c. of strong HCl, which is then diluted to half 
strength or less, or upon the residue may be poured at once a larger 
volume of acid of half strength. The dish is then covered and di- 
gestion allowed to go on for 10 minutes on the bath, after which the 
solution is filtered and the separated silica washed thoroughly with 
water. The filtrate is again evaporated to dryness, the residue 
without further heating taken up with acid and water, and the small 
amount of silica it contains separated on another filter paper. The 
papers containing the residue are transferred wet to a weighed 
platinum crucible, dried, ignited, first over a Bunsen burner until 

^ The original method was reported in the Journal of the Society for Chemical 
Industry, vol. 21, p. 30, but the method was subsequently modified by the com- 
mittee, and the above text practically conforms to that in the Engineering Record, 
vol. 48, p. 49; Engineering News, vol. 50, p. 60. 

^ If a limestone, 0.75 gram should be used, the approximate equivalent of 0.5 
gram of cement. 

^ If anything remains undecomposed it should be separated, fused with a 
little Na2C63, dissolved and added to the original solution. Of course a small 
amount of separated non-gelatinous silica is not to be mistaken for undecomposed 
matter. 

13 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

the carbon of the filter is completely consumed, and finally over the 
blast for 15 minutes and checked by a further blasting for 10 minutes 
or to constant weight. 

The silica, if great accuracy is desired, is treated in the crucible 
with about 10 c.c. of HF and 4 drops^ H2SO4 and evaporated over 
a low flame to complete dryness. The small residue is finally 
blasted for a minute or two, cooled, and weighed. The difference 
between this weight and the weight previously obtained gives the 
amount of silica.^ 

Alumina and Iron (AI2O3 and FeOs). — The filtrate, about 250 
c.c. from the second evaporation for Si02, is made alkaline with 
NH4OH after adding HCl, if need be, to insure a total of 10 to 15 
c.c. strong acid,^ and boiled to expel excess of NH3, or until there 
is but a faint odor of it, and the precipitated iron and aluminum 
hydroxides, after settling, are washed once by decantation and 
slightly on the filter. Setting aside the filtrate, the precipitate is 
dissolved in hot dilute HCl, the solution passing into the beaker 
in which the precipitation was made. The aluminum and iron 
are then reprecipitated by NH4OH6, boiled, and the second pre- 
cipitate collected and washed on the filter used in the first instance. 
The filter paper with the precipitate is then placed in a weighed 
platinum crucible {the one containing the residue from the silica if 
this was corrected hy hydrofluoric acid treatment), the paper burned 
off, and the precipitate, ignited and finally blasted 5 minutes, with 
care to prevent reduction, cooled and weighed as Al203 + Fe203.^ 

Iron (Fe203). — The combined iron and aluminum oxides are 
fused in a platinum crucible at a very low temperature with about 
3 to 4 grams KHSO4, or, better, NaHS04,^ the melt taken up 
with so much dilute H2SO4 that there shall be no less than 5 grams 
absolute acid and enough water to effect solution on heating. The 
solution is then evaporated and eventually heated till acid fumes 
come off copiously. After cooling and redissolving in water the 



'* 5 ex. HF and 2 drops HiSOa are sufficient. 

^ For ordinary control in the plant laboratory this correction may, perhaps, 
be neglected; the double evaporation never. The silica so found does not repre- 
sent quite all in the material under analysis; a little has passed into the filtrate. 
Account should be taken of a possible loss in weight of the crucible itself, if the blast is 
very powerful. 

^ And 2 or 3 c.c. of bromine water. Bromine water is used for the purpose of 
collecting practically all the manganese here, instead of allowing it to distribute among 
several different precipitates. 

^ This precipitate contains Ti02, P2O5, Mn304. 

^ Or the corresponding pyrosulphates which are less troublesome and more 
effective than the acid sulphates. 

14 



1 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

small amount of silica is filtered out, weighed and corrected by HF 
and H2S04.^ The filtrate is reduced by zinc, or preferably by 
hydrogen sulphide, boiling out the excess of the latter afterwards 
while passing CO2 through the flask, and titrated with perman- 
ganate. ^° 

The strength of the permanganate solution should not be greater 
than 0.0040 g FeoOs per c.c. 

Lime (CaO). — To the combined filtrate from the AI2O3 + Fe203 
precipitate a few drops of NH4OH are added, and the solution 
brought to boiling. To the boiling solution 20 c.c. of a saturated 
solution of ammonium oxalate is added, and the boiling continued 
until the precipitated CaC204 assumes a well-defined granular form. 
It is then allowed to stand for 20 minutes, or until the precipitate 
has settled, and then filtered and washed. The precipitate and 
filter are placed wet in a platinum crucible, and the paper is burned 
off over a small flame of a Bunsen burner. It is then ignited, re- 
dissolved in HCl, and the solution is made up to 100 c.c. wath water. 
Ammonia is added in slight excess, and the liquid is boiled. If a 
small amount of AI2O3 separates this is filtered out, weighed, and 
the amount added to that found in the first determination, when 
greater accuracy is desired. The lime is then reprecipitated by 
ammonium oxalate, allowed to stand until settled, filtered and 
washed, ^^ weighed as oxide after ignition and blasted in a covered 
crucible to constant weight, or determined with dilute standard 
permanganate.^^ 

Magnesia (MgO). — The combined filtrates from the calcium 
precipitates are acidified with HCl and concentrated on the steam 
bath to about 150 c.c, 10 c.c. of saturated solution of Na (NH4)- 
HPO4 is added, and the solution boiled for several minutes. It is 
then removed from the flame and cooled by placing the beaker in 
ice water. After cooling, NH4OH is added, drop by drop, with 
constant stirring until the crystalline ammonium-magnesium 
orthophosphate begins to form, and then in moderate excess, the 
stirring being continued for several minutes. It is then set aside 

^ This correction of AI2O3, Fe-iOz for silica should not be made when the HF 
correction of the main siUca has been omitted, unless that silica was obtained by 
only one evaporation and filtration. After two evaporations and filtrations i to 2 
mg. of Si02 are still to be found with the AI2O3, FeoOs. 

'° In this way only is the influence of titanium to be avoided and a correct 
result obtained for iron. 

^^ The volume of wash water should not be too large; vide Hillebrand, 
United States Geological Survey, Bull. 422, p. no. 

^ The accuracy of this method admits of criticism, but its convenience and 
rapidity demand its insertion. 

15 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

for several hours in a cool atmosphere and filtered. The pre- 
cipitate is redissolved in hot dilute HCl, the solution made up to 
about 100 C.C., I c.c. of a saturated solution of Na (NH4)HP04 
added, and ammonia, drop by drop, with constant stirring until 
the precipitate is again formed as described and the ammonia is 
in moderate excess. It is then allowed to stand for about 2 hours, ^^ 
when it is filtered on a paper or a Gooch crucible, ignited, cooled, 
and weighed as Mg2P207. 

The pyrophosphate invariably contains calcium which can he de- 
termined as follows: 

Dissolve the ignited pyrophosphate in a little dilute H^SO^ and add 
enough absolute alcohol to make about go to 95 per cent of the final 
volume. After several hours collect the small and sometimes almost 
invisible precipitate of calcium sulphate on a small filter and wash 
it free of phosphoric acid with alcohol. Dry the filter and extract from 
it the precipitate by a few cubic centimeters of hot water acidulated with 
HCl. Make this solution alkaline with ammonia, throw in a few 
crystals of ammonium oxalate and continue heating till a precipitate 
becomes visible. After an hour filter, wash and ignite to calcium oxide. 
Its weight, averaging perhaps o.S mg., is to be added to that of the lime 
already found and subtracted as tricalcium phosphate {not pyrophos- 
phate) from that of the magnesium pyrophosphate. 

In order to determine approximately the iron and aluminum present 
the following procedure may be followed: 

Evaporate the alcoholic filtrate from the calcium sulphate and heat 
the residue to destroy separated organic matter. Take the residue up 
with a little HCl and water and when dissolved add a drop of bromine 
water. Add ammonia till the magnesia is again precipitated and let 
stand for an hour. Decant most of the supernatant liquid and add 
slowly, drop by drop, acetic acid till all fine-grained matter has dis- 
solved. Usually there will remain a little flocculent matter which is 
likely to consist in greater part or wholly of phosphates of iron and 
aluminum {and manganese if this last was not removed by bromine 
and ammonia as in the- section on Alumina and Iron Oxides). After 
ignition the precipitate often shows a reddish color. Unless great 
care is exercised this separation will lead to erroneous results, either 
by inclusion of magnesium with the impurities as weighed or by loss 
of these in consequence of using too much acetic acid. 

Alkalies (K2O and Na20). — For the determination of the 
alkalies, the well-known method of Prof. J. Lawrence Smith is to 

^^ A paper filter should always he used if the pyrophosphate is to be corrected for 
contaminations. 

16 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

be followed, either with or without the addition of CaC02 with 
NH4CI. 

Sulphuric Anhydride Acid (SO3). — One gram of the substance 
is dissolved in 15 c.c. (5 c.c.) of HCl, and 45 ex. water, filtered, and 
the residue washed thoroughly. ^^ 

The solution is made up to 250 c.c. in a beaker and boiled. To 
the boiling solution 10 c.c. of a saturated solution of BaC^^^ is 
added slowly, drop by drop, from a pipette and the boiling con- 
tinued until the precipitate is well formed, or digested on the steam 
bath may be substituted for the boiling. It is then set aside over- 
night, or for a few hours, filtered, ignited, and weighed as BaS04. 

Total Sulphur. — One gram of the material is weighed out in a 
large platinum crucible and fused with Na2C03 and a little KNO3, 
being careful to avoid contamination from sulphur in the gases 
from source of heat. This may be done by fitting the crucible in a 
hole in an asbestos board. 

The melt is treated in the crucible with boiling water and the 
liquid poured into a tall narrow beaker and more hot water added 
until the mass is disintegrated. The solution is then filtered. 
The filtrate contained in a No. 4 beaker is to be acidulated with 
HCl and made up to 250 c.c. with distilled water, boiled, the sul- 
phur precipitated as BaS04 and allowed to stand overnight, or 
for a few hours. 

The following procedure is in accordance with the recommendation 
of W. F. Hillebrand in United States Geological Survey, Bulletin 422, 
page 22'/: 

In a platinum crucible mix i gram of the sample with one-half gram 
of sulphur -free sodium carbonate. Place the covered crucible in a hole 
in an asbestos board that is held in a somewhat inclined position and 
apply a blast flame upon the crucible below the asbestos for 10 to 75 
minutes. Transfer the sintered mass to a beaker and cover with water. 
Cleanse the crucible with dilute hydrochloric acid and pour the solution 
into the beaker. Add more acid till decomposition is complete in the 
cold or on gently warming. Filter, wash with hot water, dilute to 150 
to 200 c.c, boil, and precipitate with barium chloride. 

It should be borne in mind that by neither of the methods given is a 
barium sulphate obtained that is perfectly pure. Ferric {and if present 
alkali) sulphate, also barium chloride, contaminate it and it is im- 

^^ Evaporation to dryness is unnecessary unless gelatinous silica should 
have separated, and should never be performed on a bath heated by gas; vide 
Hillebrand : United States Geological Survey, Bulletin 422, p. iq8. 

^^ Ten per cent, solution is preferable to one that is saturated^ 

17 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

possible to correct for them directly. The most convenient way to 
obtain a correction is by a blank with a solution containing sulphur 
and the other main constituents of the cement in approximately the 
amounts and proportions found in the test sample. 

Loss on Ignition. — Half a gram of cement is to be weighed out 
in a {covered) platinum crucible, placed in a hole in an asbestos board 
so that about three-fifths of the crucible projects below, and blasted 
15 minutes, preferably with an inclined flame. The loss by weight, 
which is checked by a second blasting of 5 minutes, is the loss on 
ignition. 

Recent investigations have shown that large errors in results are 
often due to the use of impure distilled water and reagents. The 
analyst should, therefore, test his distilled water by evaporation 
and his reagents by appropriate tests before proceeding with his 
work. 

Insoluble Residue. — The insoluble residue^^ shall be determined on 
a i-gram sample which is digested on the steam bath in hydrochloric 
acid of approximately i.oj^ specific gravity until the cement is dis- 
solved. The residue is filtered, washed with hot water, and the filter 
paper contents digested on the steam bath in a 5 per cent solution of 
soditim carbonate. The residue is then filtered, washed with hot 
water, then with hot hydrochloric acid, approximately of 1.035 specific 
gravity, and finally with hot water, then ignited and weighed. The 
quantity so obtained is the insoluble residue. 



III. INTERPRETATION OF RESULTS 

Chemical 

The composition of normal Portland cement has been the sub- 
ject of a great deal of investigation and it can be said that the 
quantities of silica, alumina, oxide of iron, lime, magnesia, and sul- 
phuric anhydride can vary within fairly wide limits without ma- 
terially affecting the quality of the material. 

A normal American Portland cement which meets the standard 
specifications for soundness, setting time and tensile strength has 
an approximate composition within the following limits : 



^^ This determination was not considered by the Committee of the Society of 
Chemical Industry, and is reproduced from paragraph 19 of the United States 
Government specification for Portland cement. 

18 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

Per Cent 

Silica 19-25 

Alumina 5-9 

Iron oxide 2-4 

Lime 60-64 

Magnesia 1-4 

Sulphur trioxide i~i-75 

Loss on ignition 0.5-3.00 

Insoluble residue. o.i-i.oo 

It is also true that a number of cements have been made both 
here and abroad which have passed all standard physical tests in 
which these limits have been exceeded in one or more particulars, 
and it is equally true that a sound and satisfactory cement does not 
necessarily result from the above composition. 

It is probable that further investigation will give a clearer 
understanding of the constitution of Portland cement, but at present 
chemical analysis furnishes but little indication of the quality of 
the material. 

Defective cement usually results from imperfect manufacture, 
not from faulty composition. Cement made from very finely 
ground material, thoroughly mixed and properly burned, may be 
perfectly sound when containing more than the usual quantity of 
lime, while a cement low in lime may be entirely unsound due to 
careless manufacture. 

The analysis of a cement will show the uniformity in composition 
of the product from individual mills, but will furnish little or no 
indication of the quality of the material. Occasional analysis 
should, however, be made for record and to determine the quantity 
of sulphuric anhydride and magnesia present. 

The ground clinker as it comes from the mill is usually quick 
setting which requires correction. This is usually accomplished 
by the addition of a small quantity of more or less hydrated calcium 
sulphate, either gypsum or plaster of Paris. Experience and prac- 
tice have shown that an addition of 3 per cent or less is sufficient 
for the purpose. 

Three per cent of calcium sulphate (CaSOJ contains about 1.75 
per cent sulphuric anhydride (SO3) , and as this has been considered 
the maximum quantity necessary to control time of set, the speci- 
fication limits the SO3 content to 1.75 per cent. 

The specification prohibits the addition of any material subse- 
quent to calcination except the 3 per cent of calcium sulphate per- 
mitted to regulate time of set. Other additions may be difficult 
or impossible to detect even by a careful mill inspection during the 
process of manufacture, but as the normal adulterant would be 

19 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

ground raw material, an excess of "insoluble residue" would reveal 
the addition of silicious material, and an excess in ''loss on ignition" 
would point to the addition of calcareous material when either is 
added in sufficient quantity to make the adulteration profitable. 

The effect of relatively small quantities of magnesia (MgO) in 
normal Portland cement, while still under investigation, can be 
considered harmless. Earlier investigators believed that as mag- 
nesia had a slower rate of hydration than lime, the hydration of 
any free magnesia (MgO) present would occur after the cement 
had set and cause disintegration. 

The effect of magnesia was considered especially injurious when 
the cement was exposed to the action of sea water. More recent 
investigation has shown that cement can be made which is perfectly 
sound under all conditions when containing 5 per cent of magnesia 
and it has also been found that the lime in Portland cement ex- 
posed to sea water is replaced by magnesia. 

The maximum limit for magnesia has been set at 4 per cent, 
as it has been established that this quantity is not injurious and it 
is high enough to permit the use of the large quantities of raw 
material available in most sections of the country. 

Physical 

Specific Gravity. — If the Le Chatelier apparatus is used for the 
determination of specific gravity, the clean volumenometer flask 
is filled with benzine free from water (which can be obtained by 
placing some calcium chloride or caustic lime in the benzine storage 
jar) to a point on the stem between zero and i cubic centimeter. 
The flask is then placed in a constant temperature bath until 
volume is constant. The usual method is to introduce 64 grams of 
cement into the flask, taking care that the powder does not adhere 
to the tube above the liquid, and to free the cement from air by 
rolling the flask in an inclined position. The flask is then replaced 
in the constant temperature bath until a constant volume is re- 
corded. 

The specific gravity is obtained from the formula: 

. _ weight of cement in grams 
^ displaced volume in cu. cm. 

The specific gravity of a Portland cement is not an indication of 
its cementing value. It w^ill vary with the constituents of the ce- 
ment, especially with the content of iron oxide. Thus the white or 
very light Portland cements, containing only a fraction of a per 

20 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

cent, of iron oxide, usually have a comparatively low specific gravity 
ranging from 3.05 to 3.15, while a cement containing 3 to 4 per cent, 
or more of iron oxide may have a specific gravity of 3.20 or even 
higher. It is materially affected by the temperature and duration 
of burning the cement, the hard-burned cement having the higher 
specific gravity. A comparatively low specific gravity does not 
necessarily indicate that a cement is underburned or adulterated, 
as large percentages of raw materials could be added to a cement 
with a normally high specific gravity before the gravity would be 
reduced below 3.10. 

If a Portland cement fresh from the mill normally has a com- 
paratively low specific gravity, upon aging it may absorb sufiicient 
moisture and carbon dioxide to reduce the gravity below 3.10. It 
has been found that this does not appreciably affect the cementing 
value of the material; in fact, many cements are unsound until 
they have been aged. Thus a redetermination is permitted upon a 
sample heated to a temperature sufficient to drive off any moisture 
which may be absorbed by the cement subsequent to manufacturing, 
but would not drive off any carbon dioxide nor correct underburning 
in the process of manufacturing the cement. 

The value of the specific gravity determination lies in the fact 
that it is easily made in the field or laboratory, and when the normal 
specific gravity of the cement is known, any considerable variation 
in quality due to underburning or the addition of foreign materials 
may be detected. 

Fineness. — Only the extremely fine powder of cement called 
flour possesses appreciable cementing qualities and the coarser 
particles are practically inert. No sieve is fine enough to determine 
the flour in a cement, nor is there any other means of accurately 
and practically measuring the flour. Some cements grind easier 
than others, thus, although a larger percentage of one cement may 
pass the 200-mesh sieve than another, the former may have a 
smaller percentage of actual flour due to the difference in the hard- 
ness and the character of the clinker, and the method used in grind- 
ing. Thus the cementing value of different cements can not be 
compared directly upon their apparent fineness through a 200- 
mesh sieve. With cement from the same mill, with similar clinker 
and grinding machinery, however, it is probable that the greater 
the percentage which passes the 200-mesh sieve the greater the per- 
centage of flour in that particular cement. 

Normal Consistency. — The quantity of water used in making 
the paste from which the pats for soundness, tests of setting, and 

21 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

the briquettes are made, is very important and may vitally affect 
the results obtained. The determination consists in measuring the 
quantity of water required to bring a cement to a certain state of 
plasticity. 

In determining the normal consistency by the ball method, after 
mixing the paste it should be formed into a ball with as little working 
as possible and a new batch of cement should be mixed for each 
trial paste. In order to obtain just the requisite quantity of paste 




20.5% TWO PER CENT eE LOW NORMAL ZL^To ON E PER CENT BELOW NORMAL 




22.57o NORMAL CONSISTENCY 





2 3.5 7o ONE PER CENT ABOVE NORMAL 



24.5% TWO PER CENT ABOVE 



Fig. I. — Appearance of Ball for Different Consistencies of Cement Paste 



to form a ball 2 inches in diameter, a measure made from a pipe 
with a 2-inch inside diameter cut i^ inches long will be found con- 
venient. The section of pipe should be open at both ends, so that 
it can be pushed down onto the paste on the mixing table and the 
excess paste cut off with the trowel. The appearance of the ball 
using the correct percentage of water for normal consistency as 
compared with a less and greater quantity of water is shown in 

Fig. I. 

22 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

Mixing. — The homogeneity of the cement paste Is dependent 
upon the thoroughness of the mixing, and this may have considerable 
influence upon the time of setting and the strength of the briquettes. 

Soundness. — The purpose of this test is to detect those qualities 
in a cement which tend to destroy the strength and durability. 
Unsoundness is usually manifested by a change in volume which 
causes cracking, swelling, or disintegration. If the pat is not 
properly made, or if it is placed where it will be subject to any drying 
during the first 24 hours, it may develop what are known as shrink- 
age cracks, which are not an indication of unsoundness and should 
not be confused with disintegration cracks, as shown in Figs. 2 and 3. 
No shrinkage cracks should develop after the first 24 or 48 hours. 





—Soundness Pat Showing 
Shrinkasre Cracks 



Fig. 3. — Soundness Pat Showing 
Disintegration Cracks 



Fig. 5. — Soundness Pat with Top Surface 
Flattened for Determining Time of Setting 



The failure of the pats to remain on the glass nor the cracking of 
the glass to which the pat is attached does not necessarily indicate 
unsoundness. In molding the pats, the cement paste should first 
be flattened on the glass and the pat formed by drawing the trowel 
from the outer edge toward the center, as shown in Fig. 4. 

Time of Setting. — -The purpose of this test is to determine the 
time which elapses from the moment water is added until the paste 
ceases to be plastic and the time required for it to obtain a certain 
degree of hardness. The determination of the "initial set" or 
when plasticity ceases is the more important, as a disturbance of 
the material after this time may cause a loss of strength and thus 
it is important that the mixing and molding or the incorporating 

23 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

of the material into the work be accompHshed within this time. 
The time of setting is usually determined upon one of the pats which 
is to be used for the soundness test, the top surface being flattened 
somewhat, as shown in Fig. 5. In using the Gillmore needles care 
should be taken to apply the needles in a vertical position and 
perpendicular to the surface of the pat. Fig. 6 shows an arrange- 
ment for mounting the Gillmore needles so that they are always 
perpendicular to the surface of the pat. The rate of setting and 
hardening may be materially affected by slight changes in tem- 
perature. The percentage of water used in gauging and the hu- 








■---^ 



"•4^!^ 



Fig. 4. — Correct Method of Molding Cement Pat 

midity of the moist closet in which the test pieces are stored may 
also affect the setting somewhat. 

Tensile Tests. — Consistent results can only be obtained by 
exercising great care in molding and testing the briquettes. The 
correct method of filling the mold is shown in Figs. 7 and 8. In 
testing, the sides of the briquettes and the clips should be thoroughly 
cleaned and free from grains of sand or dirt which would prevent 
a good bearing, and the briquette should be carefully centered in 
the clips so as to avoid cross strains. It may be considered good 
laboratory practice if the individual briquettes of any set do not 
show a greater variation from the mean value than 8 per cent for 
sand mixtures and 12 per cent for neat mixtures. 

24 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

IV. AUXILIARY SPECIFICATIONS 

Bureau of Standards Sieve Specifications 
Wire cloth for standard sieves for cement and sand shall be 

woven (not twilled) from brass, bronze, or other suitable wire, and 

mounted on the frames without distortion. 

The sieve frames shall be circular, about 20 centimeters (7.87 

inches) in diameter, 6 centimeters (2.36 inches) high, and provided 

with a pan about 5 centimeters (1.97 inches) deep and a cover. 



-Ci. 





Fig. 6. — Method of Mounting Gillmore Needles 

No. 100 Cement Sieve, 0.0055-Inch Opening. — The No. 100 
sieve should have 100 wires per inch and shall conform to the follow- 
ing specifications of diameter of wire and size of mesh : 

The diameter of the wires in the sieve should be 0.0045 ii^ch 
and the average diameter of such wires as may be measured shall 
not be outside the limits 0.0042 to 0.0048 inch for either warp or 
shoot wires. The number of warp wires per whole inch, as measured 
at any point of the sieve, shall not be outside the limits 98 to lOi 

25 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

per inch, and of the shoot wires 96 to 102 per inch. For any in- 
terval of 0.25 to 0.50 inch in which the mesh may be measured the 
mesh shall not be outside the limits 95 to loi wires per inch for the 
warp wires and 93 to 103 wires per inch for the shoot wires. 

No. 200 Cement Sieve, 0.0029-Inch Opening. — The No. 200 
sieve should have 200 wires per inch and shall conform to the fol- 
lowing specifications of diameter of wire and size of mesh : 

The diameter of the wires in the sieve should be 0.0021 inch, 
and the average diameter of such wires as may be measured shall 
not be outside the limits 0.0019 to 0.0023 inch for either warp or 
shoot wires. The number of warp wires per whole inch, as measured 
at any point of the sieve, shall not be outside the limits 195 to 202 




Fig. 7. — Correct Method of Filling Briquette Mold 



per inch, and of the shoot wires 192 to 204 per inch. For any in- 
terval of 0.25 to 0.50 inch in which the mesh may be measured the 
mesh shall not be outside the limits 192 to 203 wires per inch for 
the warp wires and 190 to 205 wires per inch for the shoot wires. 

No. 20 Sand Sieve, 0.0335-Inch Opening. — No. 20 sieves shall 
have between 19.5 and 20.5 wires per whole inch of the warp wires 
and between 19 and 21 wires per inch of the shoot wires. The 
diameter of the wire should be 0.0165 inch and the average as 
measured shall not vary outside the limits 0.0160 to 0.0170 inch. 

No. 30 Sand Sieve, 0.0223-Inch Opening. — No. 30 sieves shall 
have between 29.5 and 30.5 wires per whole inch of the warp wires 

26 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

and between 28.5 and 31.5 per whole Inch of the shoot wires. The 
diameter of the wire should be o.oiio inch and the average as 
measured shall not vary outside the limits 0.0105 to 0.0 11 5 inch. 

Bureau of Standards Specification for Specific-gravity 

Flasks 
Material and Annealing.— The material from which the flasks 
are made shall be glass of the best quality, transparent, and free 
from striae. It shall adequately resist chemical action and have 
small thermal hysteresis. The flasks shall be thoroughly annealed 
at 400° C. to 500° C. for 24 hours and allowed to cool slowly before 




^"^ 



Fig. 8. — Correct Method of Troweling Surface of Briquettes 

being graduated. They shall be of sufficient thickness to insure 
reasonable resistance to breakage. 

Design. — The cross-section of the flask shall be circular and the 
shape and dimensions shall conform to the diagram shown in Fig. 
9. This design is intended to insure complete drainage of the flask 
on emptying and stability of standing on a level surface, as well as 
accuracy and precision of reading. The neck of the flask shall be 
cylindrical for at least i centimeter above and below every gradua- 
tion mark. There shall be a space of at least i centimeter between 
the highest graduation mark and the lowest point of the grinding 
for the glass stopper. . 

27 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

Capacity. — The flask should contain approximately 250 c.c. 
when filled to the zero graduation mark. 

Graduations. — The neck shall be graduated from o to i c.c. 

SPECIFIC GRAVITY FLASK 




CAPACITY OF BULK 
APPROX. 250 C C 



Fig. 9. — Diagram Showing Form and Dimensions of Specific-Gravity Flask 



and from 18 c.c. to 24 c.c. into o.i-c.c. divisions. The o.i-c.c. 
graduations should be continued two below the o and two above 

28 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 



the i-c.c. graduation. The graduations shall be of uniform width, 
finely but distinctly etched, and shall be perpendicular to the axis 
of the flask. The o.i-c.c. graduations shall be at least i millimeter 
apart. This will require an internal diameter of the neck not 
greater than 11.3 millimeters. The i-c.c. graduations shall extend 
completely around the neck of the flask and shall be numbered to 
indicate the capacity. The o.i-c.c. graduations shall extend at 
least halfway around the neck and the 0.5-c.c. graduations shall 
have a length about midway between the other two. The gradua- 
tion marks shall have no apparent irregularities of spacing. 




Fig, 10. — Form of Briquette as Recommended by the Committee on Uniform 
Tests of Cement of the American Society of Civil Engineers 

Standard Temperature. — The flasks shall be standard at 20° C. 
The indicated specific gravities will then be at 20° referred to water 
at 4° as unity — that is, density at 20° in grams per c.c. 

Inscriptions. — Each flask shall bear a permanent identification 
number and the stopper shall bear the same number. The standard 
temperature shall be indicated and the unit of capacity shall be 
shown by the letters "c.c." placed above the highest graduation 
mark. 

2& 



GOVERNMENT SPECIFICATION FOR PORTLAND CEMENT 

Tolerance. — The error of any indicated capacity shall not be 
greater than 0.05 c.c. 

Interpretation of Specification. — The foregoing specification is 
intended to represent the most desirable form of specific gravity 
flask for use in testing cements. Variations of a few millimeters 
in such dimensions as total height of flask, diameter of base, etc., 
are to be expected and will not be considered sufficient cause for 
rejection. The specification in regard to tolerance, inscriptions, 
length, spacing, and uniformity of graduations will, however, be 
rigidly enforced. 



30 



STANDARD SPECIFICATIONS FOR CEMENT 

As Adopted August i6, 1909, by the American Society for 
Testing Materials 

General Observations 

1. These remarks have been prepared with a view of pointing 
out the pertinent features of the various requirements and the pre- 
cautions to be observed in the interpretation of the results of the 
tests. 

2. The Committee would suggest that the acceptance or rejec- 
tion under these specifications be based on tests made by an ex- 
perienced person having the proper means for making the tests. 

Specific Gravity. — 3. Specific gravity is useful in detecting 
adulteration. The results of tests of specific gravity are not neces- 
sarily conclusive as an indication of the quality of a cement, but 
when in combination with the results of other tests may afford 
valuable indications. 

Fineness. — 4. The sieves should be kept thoroughly dry. 

Time of Setting. — 5. Great care should be exercised to maintain 
the test pieces under as uniform conditions as possible. A sudden 
change or wide range of temperature in the room in which the tests 
are made, a very dry or humid atmosphere, and other irregularities 
vitally affect the rate of setting. 

Constancy of Volume. — 6. The tests for constancy of volume 
are divided into two classes, the first normal, the second accelerated. 
The latter should be regarded as a precautionary test only, and not 
infallible. So many conditions enter into the making and inter- 
preting of it that it should be used with extreme care. 

7. In making the pats the greatest care should be exercised to 
avoid initial strains due to molding or to too rapid drying-out during 
the first twenty-four hours. The pats should be preserved under 
the most uniform conditions possible, and rapid changes of tem- 
perature should be avoided. 

8. The failure to meet the requirements of the accelerated 
tests need not be sufficient cause for rejection. The cement may, 

31 



STANDARD SPECIFICATIONS FOR CEMENT 

however, be held for 28 days, and a re test made at the end of that 
period using a new sample. Failure to meet the requirements at 
this time should be considered sufficient cause for rejection, although 
in the present state of our knowledge it cannot be said that such 
failure necessarily indicates unsoundness, nor can the cement be 
considered entirely satisfactory simply because it passes the tests. 

Specifications 
General Conditions. — i. All cement shall be inspected. 

2. Cement may be inspected either at the place of manufacture 
or on the work. 

3. In order to allow ample time for inspecting and testing, the 
cement should be stored in a suitable weather-tight building 
having the floor properly blocked or raised from the ground. 

4. The cement shall be stored in such a manner as to per- 
mit easy access for proper inspection and identification of each 
shipment. 

5. Every facility shall be provided by the contractor and a 
period of at least 12 days allowed for the inspection and neces- 
sary tests. 

6. Cement shall be delivered in suitable packages with the 
brand and name of manufacturer plainly marked thereon. 

7. A bag of cement shall contain 94 pounds of cement net. 
Each barrel of Portland cement shall contain 4 bags, and each 
barrel of natural cement shall contain 3 bags of the above net 
weight. 

8. Cement faihng to meet the 7-day requirements may be held 
awaiting the results of the 28-day tests before rejection. 

9. All tests shall be made in accordance with the methods pro- 
posed by the Committee on Uniform Tests of Cement of the 
American Society of Civil Engineers, presented to the Society 
January 21, 1903, amended January 20, 1904, and January 15, 
1908, with all subsequent amendments thereto.* 

10. The acceptance or rejection shall be based on the follow- 
ing requirements : 

Natural Cement. — 1 1 . Definition. — This term shall be applied to 
the finely pulverized product resulting from the calcination of an 
argillaceous limestone at a temperature only sufficient to drive off 
the carbonic acid gas. 

Fineness. — 12. It shall leave by weight a residue of not more 

* See pp. 7-22. — Ed. 
32 



STANDARD SPECIFICATIONS FOR CEMENT 

than 10 per cent on the No. lOO, and 30 per cent on the No. 200 
sieve. 

Time of Setting. — 13. It shall not develop initial set in less than 
10 minutes, and shall not develop hard set in less than 30 minutes, 
or in more than 3 hours. 

Tensile Strength. — 14. The minimum requirements for tensile 
strength for briquettes i square inch in cross section shall be as 
follows, and the cement shall show no retrogression in strength 
within the periods specified: 

Age. Neat Cement. ■ Strength. 

24 hours in moist air 75 lbs. 

7 days (i day in moist air, 6 days in water) 150 

28 days (i day in moist air, 27 days in water) 250 '' 

One Part Cement, Three Parts Standard Ottawa Sand. 

7 days (a day in moist air, 6 days in water) 50 " 

28 days (i day in moist air, 2J days in water) 125 *' 

Constancy of Volume. — 15. Pats of neat cement about 3 inches 
in diameter, one-half inch thick at center, tapering to a thin edge, 
shall be kept in moist air for a period of 24 hours. 

(a) A pat is then kept in air at normal temperature. 

Q)) Another is kept in water maintained as near 70° F. as prac- 
ticable. 

16. These pats are observed at intervals for at least 28 days, 
and, to satisfactorily pass the tests shall remain firm and hard 
and show no signs of distortion, checking, cracking or disintegrating. 

Portland Cement. — 17. Definition. — This term is appHed to the 
finely pulverized product resulting from the calcination to incipient 
fusion of an intimate mixture of properly proportioned argillaceous 
and calcareous materials, and to which no addition greater than 3 
per cent has been made subsequent to calcination. 

Specific Gravity. — 18. The specific gravity of cement shall be 
not less than 3.10. Should the test of cement as received fall 
below this requirement, a second test may be made upon a sample 
ignited at low red heat. The loss in weight of the ignited cement 
shall not exceed 4 per cent. 

Fineness. — 19. It shall leave by weight a residue of not more 
than 8 per cent on the No. loO;. and not more than 25 per cent 
on the No. 200 sieve. 

Time of Setting. — 20. It shall not develop initial set In less than 
30 minutes, and must develop hard set in not less than i hour, 
nor more than 10 hours. 

33 



STANDARD SPECIFICATIONS FOR CEMENT 

Tensile Strength. — 21. The minimum requirements for tensile 
strength for briquettes i square inch in cross section shall be as 
follows, and the cement shall show no retrogression in strength 
within the periods specified: 

Age. Neat Cement. Strength. 

24 hours in moist air 175 lbs. 

7 days (i day in moist air, 6 days in water) 500 " 

28 days (i day in moist air, 27 days in water) 600 " 

One Part Cement, Three Parts Standard Ottawa Sand. 

7 days (i day in moist air, 6 days in water) 200 " 

28 days (i day in moist air, 2^ days in water) 275 " 

Constancy of Volume. — 22. Pats of neat cement about 3 inches 
in diameter, one-half inch thick at the center, and tapering to a thin 
edge shall be kept in moist air for a period of 24 hours. 

(a) A pat is then kept in air at normal temperature and ob- 
served at intervals for at least 28 days. 

{h) Another pat is kept in water maintained as near 70° F. 
as practicable, and observed at intervals for at least 28 days. 

(c) A third pat is exposed in any convenient way in an atmos- 
phere of steam, above boiling water, in a loosely closed vessel for 
5 hours. 

23. These pats, to satisfactorily pass the requirements, shall 
remain firm and hard and show no signs of distortion, checking, 
cracking or disintegrating. 

Sulphuric Acid and Magnesia. — 24. The cement shall not con- 
tain more than 1.75 per cent of anhydrous sulphuric acid (SO.3). 
nor more than 4 per cent of magnesia (MgO). 



34 



METHODS FOR TESTING CEMENT* 

REPORT OF THE COMMITTEE OF THE AMERICAN SOCIETY OF 

CIVIL ENGINEERS, PRESENTED AT THE ANNUAL 

MEETING, JANUARY 17, 1912 

Sampling 

1. Selection -of Sample. — The selection of samples for testing 
should be left to the engineer. The number of packages sampled 
and the quantity taken from each package will depend on the Im- 
portance of the work and the facilities for making the tests. 

2. The samples should fairly represent the material. When the 
amount to be tested Is small It Is recommended that i barrel In 10 
be sampled; w^hen the amount Is large It may be Impracticable to 
take samples from more than i barrel In 30 or 50. When the sam- 
ples are taken from bins at the mill i for each 50 to 200 barrels will 
suffice. 

3. Samples should be passed through a sieve having 20 meshes 
per linear Inch, In order to break up lumps and remove foreign ma- 
terial; the use of this sieve Is also effective to obtain a thorough 
mixing of the samples when this Is desired. To determine the ac- 
ceptance or rejection of cement it is preferable, when time permits, 
to test the samples separately. Tests to determine the general 
characteristics of a cement, extending over a long period, may be 
made with mixed samples. 

4. Method of Sampling. — Cement In barrels should be sampled 
through a hole made In the head, or in one of the staves midway 
between the heads, by means of an auger or a sampling iron similar 
to that used by sugar inspectors; If In bags, the sample should be 
taken from surface to center; cement In bins should be sampled in 
such a manner as to represent fairly the contents of the bin. Samp- 
ling from bins Is not recommended If the method of manufacture 
is such that Ingredients of any kind are added to the cement sub- 
sequently. 

Chemical Analysis 

5. Significance. — Chemical analysis may serve to detect adul- 

* Accompanying Final Report of Special Committee of American Society 
of Civil Engineers on Uniform Tests of Cement, dated January 17th, 1912. 

35 



METHODS FOR TESTING CEMENT 

teration of cement with inert material, such as slag or ground lime- 
stone, if in considerable amount. It is useful in determining 
whether certain constituents, such as magnesia and sulphuric 
anhydride, are present in inadmissible proportions. 

6. The determination of the principal constituents of cement, 
silica, alumina, iron oxide, and lime, is not conclusive as an indica- 
tion of quality. Faulty cement results more frequently from im- 
perfect preparation of the raw material or defective burning than 
from incorrect proportions. Cement made from material ground 
very finely and thoroughly burned may contain much more lime 
than the amount usually present, and still be perfectly sound. On 
the other hand, cements low in lime may, on account of care- 
less preparation of the raw material, be of dangerous character. 
Furthermore, the composition of the product may be so greatly 
modified by the ash of the fuel used in burning as to affect in a great 
degree the significances of the results of analysis. 

7. Methods. — The methods to be followed, except for determin- 
ing the loss on ignition, should be those proposed by the Committee 
on Uniformity in the Analysis of Materials for the Portland Cement 
Industry, reported in the Journal of the Society for Chemical In- 
dustry, Vol. 21, page 12, 1902; and published in Engineering News, 
Vol. 50, page 60, 1903; and in Engineering Record, Vol. 48, page 49, 
1903, and in addition thereto, the following: 

{a) The insoluble residue may be determined as follows: To a 
I -gram sample of cement are added 30 cu. cm. of water and 10 
cu. cm. of concentrated hydrochloric acid, and then warmed until 
effervescence ceases, and digested on a steam bath until dissolved. 
The residue is filtered, washed with hot water, and the filter paper 
and contents digested on the steam bath in a 5% solution 'of sodium 
carbonate. This residue is filtered, washed with hot water, then 
with hot hydrochloric acid, and finally with hot water, and then 
ignited at a red heat and weighed. The quantity so obtained 
is the insoluble residue. 

{h) The loss on ignition shall be determined in the following 
manner: }4 gram of cement is heated in a weighed platinum 
crucible, with cover, for 5 minutes with a Bunsen burner (starting 
with a low flame and gradually increasing to its full height) and 
then heated for 15 minutes with a blast lamp: the difference be- 
tween the weight after cooling and the original weight is the loss on 
ignition. The temperature should not exceed 900° cent, or a low 
red heat; the ignition should preferably be made in a mufile. 

36 



methods for testing cement 

Specific Gravity 

8. Significance. — The specific gravity of cement is lowered by 
adulteration and hydration, but the adulteration must be con- 
siderable to be detected by tests of specific gravity. 

9. Inasmuch as the differences in specific gravity are usually very 
small, great care must be exercised in making the determination. 

10. Apparatus. — The determination of specific gravity should be 





Fig. I. — Le Chatelier's Specific-Gravity Apparatus 



made with a standardized Le Chatelier apparatus. This consists 
of a flask (D), Fig. i, of about 120 cu. cm. capacity, the neck of 
which is about 20 cm. long; in the middle of this neck is a bulb (C), 
above and below which are two marks (F) and (E) ; the volume 
between these two marks is 20 cu. cm. The neck has a diameter 
of about 9 mm., and is graduated into tenths of cubic centimeters 
above the mark (F). 

37 



METHODS FOR TESTING CEMENT 

11. Benzine (62° Baume naphtha) or kerosene free from water 
should be used in making the determination. 

12. Method. — The flask is filled with either of these liquids to 
the lower mark {E), and 64 grams of cement, cooled to the tempera- 
ture of the liquid, is slowly introduced through the funnel {B) (the 
stem of which should be long enough to extend into the flask to the 
top of the bulb (C)), taking care that the cement does not adhere to 
the sides of the flask, and that the funnel does not touch the Hquid. 
After all the cement is introduced, the level of the liquid will rise to 
some division of the graduated neck; this reading, plus 20 cu. cm., 
is the volume displaced by 64 grams of the cement. 

13. The specific gravity is then obtained from the formula 

Weight of cement, in grams. 

Specific gravity = — ^ -^ ^ ^ 

Displaced volume, in cubic centimeters. 

14. The flask, during the operation, is kept immersed in water 
in a jar {A), in order to avoid variation in the temperature of the 
liquid in the flask, which should not exceed }i° cent. The results of 
repeated tests should agree within o.oi. The determination of 
specific gravity should be made on the cement as received; if it 
should fall below 3.10, a second determination should be made after 
igniting the sample in a covered dish, preferably of platinum, at a 
low red heat not exceeding 900° cent. The sample should be heated 
for 5 minutes with a Bunsen burner (starting with a low flame and 
gradually increasing to its full height) and then heated for 15 
minutes with a blast lamp ; the ignition should preferably be made 
in a muffle. 

15. The apparatus may be cleaned in the following manner: 
The flask is inverted and shaken vertically until the liquid flows 
freely, and then held in a vertical position until empty; any traces 
of cement remaining can be removed by pouring into the flask a 
small quantity of clean liquid benzine or kerosene and repeating 
the operation. 

Fineness 

16. Significance. — It is generally accepted that the coarser 
particles in cement are practically inert, and it is only the extremely 
fine powder that possesses cementing qualities. The more finely 
cement is pulverized, other conditions being the same, the more sand 
it will carry and produce a mortar of a given strength. 

17. Apparatus. — The fineness of a sample of cement is deter- 
mined by weighing the residue retained on certain sieves. Those 
known as No. 100 and No. 200, having approximately 100 and 200 

38 



METHODS FOR TESTING CEMENT 

wires per linear inch, respectively, should be used. They should be 
8 inches in diameter. The frame should be of brass, 8 inches in 
diameter, and the sieve of brass wire cloth conforming to the follow- 
ing requirements: 





Diameter of wire. 


Meshes per Linear Inxh. 


No. of sieve. 


Warp. 


Woof. 


I GO 
200 


0.0042 to 0.0048 in. 
0.0021 to 0.0023 " 


95 to lOI 
192 to 203 


93 to 103 
190 to 205 



The meshes in any smaller space, down to 0.25 inch, should be 
proportional in number. 

18. Method. — The test should be made with 50 grams of cement, 
dried at a temperature of 100° cent. (212° Fahr.). 

19. The cement is placed on the No. 200 sieve, which, w^ith pan 
and cover attached, is held in one hand in a slightly inclined posi- 
tion, and moved forward and backward about 200 times per minute, 
at the same time striking the side gently, on the up stroke, against 
the palm of the other hand. The operation is contmued until not 
more than 0.05 gram will pass through in one minute. The residue 
is weighed, then placed on the No. 100 sieve, and the operation 
repeated. The work may be expedited by placing in the sieve a 
few large steel shot, which should be removed before the final one 
minute of sieving. The sieves should be thoroughly dry and clean. 

Normal Consistency 

20. Significance. — The use of a proper percentage of water in 
making pastes* and mortars for the various tests is exceedingly im- 
portant and affects vitally the results obtained. 

21. The amount of water, expressed in percentage by weight of 
the dry cement, required to produce a paste of plasticity desired, 
termed "normal consistency," should be determined w^ith the Vicat 
apparatus in the following manner: 

22. Apparatus. — This consists of a frame {A), Fig. 2, bearing a 
movable rod (B), weighing 300 grams, one end (C) being i cm. in 
diameter for a distance of 6 cm., the other having a removable 
needle (D), i mm. in diameter, 6 cm. long. The rod is reversible, 

* The term "paste" is used in this report to designate a mixture of cement 
and water, and the word "mortar" to designate a mixture of cement, sand, and 
water. 

39 



METHODS FOR TESTING CEMENT 

and can be held in any desired position by a screw (E) , and has mid- 
way between the ends a mark (F) which moves under a scale (gradu- 
ated to millimeters) attached to the frame (A). The paste is held 
in a conical, hard-rubber ring (G), 7 cm. in diameter at the base, 4 
cm. high, resting on a glass plate (H) about 10 cm. square. 

23. Method. — In making the determination, the same quantity 
of cement as will be used subsequently for each batch in making the 
test pieces, but not less than 500 grams, with a measured quantity 





Fig. 2. — Vicat Apparatus 



of water, is kneaded into a paste, as described in Paragraph 45, and 
quickly formed into a ball with the hands, completing the operation 
by tossing it six times from one hand to the other, maintained about 
6 inches apart; the ball resting in the palm of one hand is pressed 
into the larger end of the rubber ring held in the other hand, com- 
pletely filling the ring with paste; the excess at the larger end is 
then removed by a single movement of the palm of the hand; the 

40 



METHODS FOR TESTING CEMENT 

ring Is then placed on its larger end on a glass plate and the excess 
paste at the smaller end is sliced off at the top of the ring by a single 
oblique stroke of a trowel held at a slight angle with the top of the 
ring. During these operations care must be taken not to compress 
the paste. The paste confined in the ring, resting on the plate, is 
placed under the rod, the larger end of which is brought in contact 
with the surface of the paste; the scale is then read, and the rod 
quickly released. 

24. The paste is of normal consistency when the cylinder settles 
to a point 10 mm. below the original surface in one-half minute 
after being released. The apparatus must be free from all vibra- 
tions during the test. 

25. Trial pastes are made with varying percentages of water 
until the normal consistency is obtained. 

26. Having determined the percentage of water required to pro- 
duce a paste of normal consistency, the percentage required for a 
mortar containing, by weight, one part of cement to three parts of 
standard Ottawa sand, is obtained from the following table, the 
amount being a percentage of the combined weight of the cement 
and sand. 



Percentage of Water for Standard Mortars 





One cement, 




One cement, 




One cement, 


Neat. 


three standard 


Neat. 


three standard 


Neat. 


three standard 




Ottawa sand. 


1 


Ottawa sand. 




Ottawa sand. 


15 


8.0 


23 


9-3 


31 


10.7 


16 


8.2 


24 


9.5 


32 


10.8- 


17 


8.3 


25 


9-7 


33 


II.O 


18 


8.5 


26 


9.8 


34 


11.2 


19 


8.7 


27 


lO.O 


35 


11.3 


20 


8.8 


1 28 


10.2 


36 


II-5 


21 


9.0 


1 29 


10.3 


37 


11.7 


22 


9.2 


30 


10.5 


38 


11.8 



Time of Setting 
27. Significance. — The object of this test is to determine the 
time which elapses from the moment water is added until the paste 
ceases to be plastic (called the "initial set"), and also the time until 
it acquires a certain degree of hardness (called the "final set" or 
"hard set"). The former is the more important, since, with the 
commencement of setting, the process of crystallization begins. 
As a disturbance of this process may produce a loss of strength, it 
is desirable to complete the operation of mixing or moulding or in- 
corporating the mortar into the work before the cement begins to set. 

41 



METHODS FOR TESTING CEMENT 

28. Apparatus. — The initial and final set should be determined 
with the Vicat apparatus described in Paragraph 22. 

29. Method. — A paste of normal consistency is moulded in the 
hard-rubber ring, as described in Paragraph 23, and placed under the 
rod (B), the smaller end of which is then carefully brought in con- 
tact with the surface of the paste, and the rod quickly released. 

30. The initial set is said to have occurred when the needle 
ceases to pass a point 5 mm. above the glass plate; and the final 
set, when the needle does not sink visibly into the paste. 

31. The test pieces should be kept in moist air during the test; 
this may be accomplished by placing them on a rack over water con- 
tained in a pan and covered by a damp cloth ; the cloth to be kept 
from contact with them by means of a wire screen ; or they may be 
stored in a moist box or closet. 

32. Care should be taken to keep the needle clean, as the collec- 
tion of cement on the sides of the needle retards the penetration, 
while cement on the point may increase the penetration. 

33. The time of setting is affected not only by the percentage and 
temperature of the water used and the amount of kneading the 
paste receives, but by the temperature and humidity of the air, 
and its determination is, therefore, only approximate. 

Standard Sands 

34. The sand to be used should be natural sand from Ottawa, 
111., screened to pass a No. 20 sieve, and retained on a No. 30 sieve. 
The sieves should be at least 8 in. in diameter; the wire cloth 
should be of brass wire and should conform to the following re- 
quirements : 





Diameter of wire. 


Meshes per Linear Inch. 


No. of sieve. 


Warp. 


Woof. 


20 • 
30 


0.016 to 0.017 in. 
o.oii to 0.012 " 


19.5 to 20.5 
29-5 to 30.5 


19 to 21 

28.5 to 31.5 



Sand which has passed the No. 20 sieve is standard when not 
more than 5 grams passes the No. 30 sieve in one minute of continu- 
ous sifting of a 500-gram sample.* 



* This sand may now (1912) be obtained from the Ottawa SiHca Co., at a 
cost of two cents per pound, f. o. b. cars, Ottawa, 111. 

42 



methods for testing cement 

Form of Test Pieces 

35. For tensile tests the form of test piece shown in Fig. 3 
should be used. 

36. For compressive tests, 2-inch cubes should be used. 

Moulds 

37. The moulds should be of brass, bronze, or other non-cor- 




Fig. 3. — Details for Briquette 



rodible material, and should have sufficient metal in the sides to 
prevent spreading during moulding. 

38. Moulds may be either single or gang moulds. The latter 
are preferred by many. If used, the types shown in Figs. 4 and 5 
are recommended. 

39. The moulds should be wiped with an oily cloth before using. 

43 



methods for testing cement 

Mixing 

40. The proportions of sand and cement should be stated by 
weight ; the quantity of water should be stated as a percentage by 
weight of the dry material. 

41. The metric system is recommended because of the con- 
venient relation of the gram and the cubic centimeter. 

42. The temperature of the room and of the mixing water should 
be maintained as nearly as practicable at 21° cent. (70° Fahr.). 




J. 



Fig. 4. — Details for Gang Mould 

43. The quantity of material to be mixed at one time depends on 
the number of test pieces to be made; 1000 grams is a convenient 
quantity to mix by hand methods. 

44. The Committee has investigated the various mechanical 
mixing machines thus far devised, but cannot recommend any of 
them, for the following reasons: (i) the tendency of most cement 
is to "ball up" in the machine, thereby preventing working it 
into a homogeneous paste; (2) there are no means of ascertaining 
when the mixing is complete without stopping the machine; and 
(3) it is difficult to keep the machine clean. 




Fig. 5. — Mould for Compression Test Pieces 



45. Method. — The material is weighed, placed on a non-ab- 
sorbent surface (preferably plate glass), thoroughly mixed dry if 
sand be used, and a crater formed in the center, into which the 
proper percentage of clean water is poured; the material on the 
outer edge is turned into the center by the aid of a trowel. As 
soon as the water has been absorbed, which should not require more 
than one minute, the operation is completed by vigorously kneading 

44 



METHODS FOR TESTING CEMENT 

with the hands for one minute. During the operation the hands 
should be protected by rubber gloves. 

Moulding 

46. The Committee has not been able to secure satisfactory re- 
sults with existing moulding machines; the operation of machine 
moulding is very slow ; and is not practicable with pastes or mortars 
containing as large percentages of water as herein recommended. 

47. Method. — Immediately after mixing, the paste or mortar is 
placed in the moulds with the hands, pressed in firmly with the 
fingers, then smoothed off with a trowel without ramming. The 
material should be heaped above the mould, and, in smoothing off, 
the trowel should be drawn over the mould in such a manner as to 
exert a moderate pressure on the material. The mould should then 
be turned over and the operation of heaping and smoothing off 
repeated. 

48. A check on the uniformity of mixing and moulding may be 
afforded by weighing the test pieces on removal from the moist 
closet; test pieces from any sample which vary in weight more than 
3 per cent from the average should not be considered. 

Storage of the Test Pieces 

49. During the first 24 hours after moulding, the test pieces 
should be kept in moist air to prevent drying. 

50. Two methods are in common use to prevent drying: (i) 
covering the test pieces with a damp cloth, and (2) placing them in a 
moist closet. The use of the damp cloth, as usually carried out, is 
objectionable, because the cloth may dry out unequally and in con- 
sequence the test pieces will not all be subjected to the same degree 
of moisture. This defect may be remedied to some extent by im- 
mersing the edges of the cloth in water; contact between the cloth 
and the test pieces should be prevented by means of a wire screen 
or some similar arrangement. A moist closet is so much more 
effective in securing uniformly moist air, and is so easily devised and 
so inexpensive, that the use of the damp cloth should be abandoned. 

51. A moist closet consists of a soapstone or slate box, or a 
wooden box lined with metal, the interior surface being covered with 
felt or broad wicking kept wet, the bottom of the box being kept 
covered with water. The interior of the box is provided with glass 
shelves on which to place the test pieces, the shelves being so ar- 
ranged that they may be withdrawn readily. 

52. After 24 hours in moist air, the pieces to be tested after 

45 



METHODS FOR TESTING CEMENT 

longer periods should be immersed in water in storage tanks or 
pans made of non-corrodible material. 

53. The air and water in the moist closet and the water in the 
storage tanks should be maintained as nearly as practicable at 21° 
cent. (70° Fahr.). 

Tensile Strength 

54. The tests may be made with any standard machine. 




SECTION A-B 

Roller turned and accurately 

bored to easy tuiuinK fit 



FORM OF CLIP 



Fig. 6 



55. The clip is shown in Fig. 6. It must be made accurately, 
the pins and rollers turned, and the rollers bored slightly larger 
than the pins so as to turn easily. There should be a slight clearance 
at each end of the roller, and the pins should be kept properly 
lubricated and free from grit. The clips should be used without 
cushioning at the points of contact. 

46 



METHODS FOR TESTING CEMENT 

56. Test pieces should be broken as soon as they are removed 
from the water. Care should be observed in centering the test 
pieces in the testing machine, as cross strains, produced by imperfect 
centering, tend to lower the breaking strength. The load should 
not be applied too suddenly, as it may produce vibration, the shock 
from which often causes the test piece to break before the ultimate 
strength is reached. The bearing surfaces of the clips and test 
pieces must be kept free from grains of sand or dirt, which would 
prevent a good bearing. The load should be applied at the rate 
of 600 lbs. per min. The average of the results of the test pieces 
from each sample should be taken as the test of the sample. Test 
pieces which do not break within % in. of the center, or are other- 
wise manifestly faulty, should be excluded in determining average 
results. 

Compressive Strength 

57. The tests may be made with any machine provided with 
means for so applying the load that the line of pressure is along the 
axis of the test piece. A ball-bearing block for this purpose is shown 
in Fig. 7. Some appliance should be provided to facilitate placing 
the axis of the test pieces exactly in line with the center of the ball- 
bearing. 

58. The test piece should be placed in the testing machine, with 
a piece of heavy blotting paper on each of the crushing faces, which 
should be those that were in contact with the mould. 

Constancy of Volume 

59. Significance. — The object is to detect those qualities which 
tend to destroy the strength and durability of a cement. Under 
normal conditions these defects will in some cases develop quickly, 
and in other cases may not develop for a considerable time. Since 
the detection of these destructive qualities before using the cement 
in construction is essential, tests are made not only under normal 
conditions but under artificial conditions created to hasten the de- 
velopment of these defects. Tests may, therefore, be divided into 
two classes: (i) Normal tests, made in either air or water main- 
tained, as nearly as practicable, at 24° cent. (70° Fahr.) ; and (2) 
Accelerated tests, made in air, steam or water, at temperatures of 
45° cent. (113° Fahr.) and upward. The Committee recommends 
that these tests be made in the following manner : 

60. Methods. — Pats, about 3 inches in diameter, yi in. thick 
at the center, and tapering to a thin edge, should be made on clean 

47 



METHODS FOR TESTING CEMENT 

glass plates (about 4 in. square) from cement paste of normal con- 
sistency, and stored in a moist closet for 24 hours. 

61. Normal Tests. — After 24 hours in the moist closet, a pat is 
immersed in water for 28 days and observed at intervals. A similar 
pat, after 24 hours in the moist closet, is exposed to the air for 28 
days or more and observed at intervals. 

62. Accelerated Test. — ^After 24 hours in the moist closet, a pat 
is placed in an atmosphere of steam, upon a wire screen i in. above 




Head of Testing Machine 
Fig. 7. — Ball-bearing Block for Testing Machine 



boiling water, for 5 hours. The apparatus should be so constructed 
that the steam will escape freely and atmospheric pressure be main- 
tained. Since the type of apparatus used has a great influence on 
the results, the arrangement shown in Fig. 8 is recommended. 

63. Pats which remain firm and hard and show no signs of crack- 
ing, distortion, or disintegration are said to be '*of constant volume" 
or "sound." 

64. Should the pat leave the plate, distortion may be detected 

48 



METHODS FOR TESTING CEMENT 



B-S 



rj^ 



n-^ 



g-^:!— ^ 



r 



7,9— 



I 



O 



TTJ 



^s^ 



-SI- 



d 






O ^ 



tv 



'5 s 



■aSVn 







49 



METHODS FOR TESTING CEMENT 

best with a straight-edge applied to the surface which was in contact 
with the plate. 

65. In the present state of our knowledge it cannot be said that 
a cement which fails to pass the accelerated test will prove defective 
in the work ; nor can a cement be considered entirely safe simply be- 
cause it has passed these tests. 

George S. Webster, Chairman, 

Richard L. Humphrey, Secretary. 

W. B. W. Howe, 

F. H. Lewis, 

S. B. Newberry, 

Alfred Noble, 

Clifford Richardson, 

L. C. Sabin, 

George F. Swain. 



50 



METHODS FOR TESTING CEMENT* 

Condensed for Use in Specifications 

1 . Sampling. — Cement in barrels shall be sampled through a hole 
made in the head, or in one of the staves midway between the heads, 
by means of an auger or a sampling iron similar to that used by 
sugar inspectors; if in bags, the sample shall be taken from surface 
to center. Cement in bins shall be sampled in such a manner as to 
represent fairly the contents of the bin. The number of samples 
taken shall be as directed by the Engineer, who will determine 
whether the samples shall be tested separately or mixed. 

The samples shall be passed through a sieve having 20 meshes 
per linear inch, in order to break up lumps and remove foreign 
material. 

2. Chemical Analysis. — The methods to be followed, except 
for determining the loss on ignition should be those proposed by the 
Committee on Uniformity in the Analysis of Materials for the 
Portland Cement Industry, reported in the Journal of the Society 
for Chemical Industry, Vol. 21, p. 12, 1902, and published in En- 
gineering News, Vol. 50, p. 60, 1903, and in Engineering Record, 
Vol. 48, p. 49, 1903, and in addition thereto the following: 

{a) The insoluble residue may be determined as follows: To 
a I -gram sample of the cement are added 30 cu. cm. of water and 
10 cu. cm. of concentrated hydrochloric acid, and then warmed until 
effervescence ceases, and digested on a steam bath until dissolved. 
The residue is filtered, washed with hot water, and the filter paper 
and contents digested on the steam bath in a 5% solution of sodium 
carbonate. This residue is filtered, washed with hot water, then 
with hot hydrochloric acid, and finally with hot water, and then 
ignited at a red heat and weighed. The quantity so obtained is 
the insoluble residue. 

(&) The loss on ignition shall be determined in the following 
manner : }4 gram of cement is heated in a weighed platinum cruci- 
ble, with cover, for 5 minutes with a Bunsen burner (starting with 
a low flame and gradually increasing to its full height) and then 
heated for 1 5 minutes with a blast lamp ; the difference between the 

* Accompanying Final Report of Special Committee on Uniform Tests of 
Cement, dated January 17th, 1912. 

51 



METHODS FOR TESTING CEMENT 

weight after cooling and the original weight is the loss on ignition. 
The temperature should not exceed 900° cent., or a low red heat; 
the ignition should preferably be made in a muffle. 

3. Specific Gravity. — The determination of specific gravity shall 
be made with a standardized Le Chatelier apparatus. This con- 
sists of a flask {D), Fig. i, page 37, of about 120 cu. cm. capacity, 
the neck of which is about 20 cm. long; in the middle of this neck 
is a bulb (C), above and below which are two marks {F) and {E) ; 
the volume between these two marks is 20 cu. cm. The neck has 
a diameter of about 9 mm., and is graduated into tenths of cubic 
centimeters above the mark {F). 

Benzine (62° Baume naphtha) or kerosene free from water 

shall be used in making the determination. The flask is filled with 

either of these liquids to the lower mark {E) and 64 grams of cement, 

cooled to the temperature of the liquid, is slowly introduced through 

the funnel {B) (the stem of which should be long enough to extend 

into the flask to the top of the bulb (C), taking care that the cement 

does not adhere to the sides of the flask, and that the funnel does 

not touch the liquid. After all the cement is introduced, the level 

of the liquid will rise to some division of the graduated neck; this 

reading, plus 20 cu. cm., is the volume displaced by 64 grams of 

the cement. The specific gravity is obtained from the formula, 

^ .^ . Weight of cement, in grams, 

bpecinc gravity = :pr^ — -. -. ^ : — -. v-. -. 

Displaced volume, m cubic centimeters. 

The flask, during the operation, is kept immersed in water in a 
jar {A), in order to avoid variations in the temperature of the liquid 
in the flask, which should not exceed >2° cent. The results of re- 
peated tests should agree within o.oi. 

The determination of specific gravity shall be made on the ce- 
ment as received; if it should fall below 3.10, a second determina- 
tion shall be made after igniting the sample at a low red heat. The 
ignition shall be carried out in the following manner: 

The flask, during the operation, is kept immersed in water in a 
jar {A) in order to avoid variations in the temperature of the liquid 
in the flask, which should not exceed >^° cent. The results of re- 
peated tests should agree within o.oi . The determination of specific 
gravity^ should be made on the cement as received ; if it should fall 
below 3.10, a second determination should be made after igniting 
the sample in a covered dish, preferably of platinum, at a low red 
heat not exceeding 900° cent. The sample should be heated for 5 
minutes with a Bunsen burner (starting with a low flame and grad- 
ually increasing to its full height) and then heated for 15 minutes 

52 



I 



METHODS FOR TESTING CEMENT 

with a blast lamp; the ignition should preferably be made in a 
muffle. 

4. Fineness. — The fineness shall be determined by weighing 
the residue retained on No. 100 and No. 200 sieves. The sieves, 
8 inches in diameter, shall be of brass wire cloth conforming to the 
following requirements : 





Diameter of wire. 


Meshes per Linear Inch. 


No. of sieve. 


Warp. 


Woof. 


100 
200 


0.0042 to 0.0048 in. 

0.0021 to 0.0023 " 


93 to loi 
192 to 203 


93 to 103 • 
190 to 205 



The meshes in any smaller space, down to 0.25 inch, shall be 
proportional in number. 

Fifty grams of cement, dried at a temperature of 100° cent. (212° 
Fahr.), shall be placed on the No. 200 sieve, which with pan and 
cover attached, is held in one hand in a slightly inclined position, 
and moved forward and backward about 200 times per minute, at 
the same time striking the side gently, on the up stroke, against the 
palm of the other hand. The operation is continued until not 
more than 0.05 gram will pass through in one minute. The residue 
is weighed, then placed on the No. 100 sieve, and the operation re- 
peated. The work may be expedited by placing in the sieve a 
few large steel shot, which should be removed before the final one 
minute of sieving. The sieves should be thoroughly dry and clean. 

5. Normal Consistency. — ^The amount of water, expressed in 
percentage by weight of the dry cement, required to produce a 
paste* of the plasticity desired, termed "normal consistency," 
shall be determined with the Vicat apparatus : 

This consists of a frame (A), Fig. 2, page 40, bearing a movable 
rod (B), weighing 300 grams, one end (C) being i cm. in diameter 
for a distance of 6 cm., the other having a removable needle (D), 
I mm. in diameter, 6 cm. long. The rod is reversible, and can be 
held in any desired position by a screw (E), and has midway be- 
tween the ends a mark (F) which moves under a scale (graduated 
to millimeters) attached to the frame (A). The paste is held in a 
conical, hard-rubber ring (G), 7 cm. in diameter at the base, 4 cm. 
high, resting on a glass plate (H) about 10 cm. square. 

* The term "paste" is used in these specifications to designate a mixture of 
cement and water, and the word "mortar" to designate a mixture of cement, 
sand, and water. 

53 



METHODS FOR TESTING CEMENT 

In making the determination of normal consistency, the same 
quantity of cement as will be used subsequently for each batch in 
making the test pieces, but not less than 500 grams, together with a 
measured amount of water, is kneaded into a paste, as described in 
Section 9, and quickly formed into a ball with the hands, completing 
the operation by tossing it six times from one hand to the other 
maintained about 6 in. apart; the ball resting in the palm of 
one hand is pressed into the larger end of the rubber ring held in 
the other hand, completely filling the ring with paste; the excess at 
the larger end is then removed by a single movement of the palm 
of the hand ; the ring is then placed on its larger end on a glass plate 
and the excess paste at the smaller end is sliced off at the top of the 
ring by a single oblique stroke of a trowel held at a slight angle 
with the top of the ring. During these operations care must be 
taken not to compress the paste. The paste confined in the ring, 
resting on the plate, is placed under the rod, the larger end of which 
is carefully brought in contact with the surface of the paste; the 
scale is then read, and the rod quickly released. 

The paste is of normal consistency when the cylinder settles to a 
point 10 mm. below the original surface in one-half minute after 
being released. The apparatus must be free from all vibrations 
during the test. 

Trial pastes are made with varying percentages of water until 
the normal consistency is attained. 

Having determined the percentage of water required to produce a 
paste of normal consistency, the percentage required for a mortar 
containing, by weight, one part of cement to three parts of standard 
Ottawa sand, shall be obtained from the following table, the amount 
being a percentage of the combined weight of the cement and sand. 





Percentage 


OF Water for Standard Mortars 






One cement, 




One cement, 




One cement, 


Neat. 


three standard 


Neat, 


three standard 


Neat. 


three standard 




Ottawa sand. 




Ottawa sand. 




Ottawa sand. 


15 


8.0 


23 


9-3 


31 


10.7 


16 


8.2 


24 


9.5 


32 


10.8 


17 


8.3 


25 


9-7 


33 


II.O 


18 


8.5 


26 


9.8 


34 


II. 2 


19 


8.7 


27 


lO.O 


35 


II.3 


20 


8.8 


28 


10.2 


36 


II-5 


21 


9.0 


29 


10.3 


37 


II. 7 


22 


9.2 


30 


10.5 


38 


II. 8 



54 



METHODS FOR TESTING CEMENT 

6. Time of Setting. — The time of setting shall be determined 
with the Vicat apparatus in the following manner: 

A paste of normal consistency is moulded in the hard-rubber 
ring, as described in Section 5, and placed under the rod (B), the 
smaller end of which is then carefully brought in contact with the 
surface of the paste, and the rod quickly released. 

The cement is considered to have acquired its initial set when 
the needle ceases to pass a point 5 mm. above the glass plate; and 
the final set, when the needle does not sink visibly into the paste. 

The test pieces must be kept in moist air during the test. 

7. Standard Sand. — The sand shall be natural sand from 
Ottawa, 111., screened to pass a No. 20 sieve, and retained on a No. 
30 sieve. 

The sieves shall be at least 8 in. in diameter, and the wire 
cloth shall be of brass wire and shall conform to the following re- 
quirements : 





Diameter of wire. 


Meshes per Linear Inch, 


No. of sieve. 


Warp. 


Woof. 


20 
30 


0.016 to 0.017 in. 
o.oii to 0.012 " 


19.5 to 20.5 
29.5 to 30.5 


19 to 21 

28.5 to 31.5 



Sand which has passed the No. 20 sieve Is standard when not 
more than 5 grams passes the No. 30 sieve in one minute of con- 
tinuous sifting of a 500-gram sample.* 

8. Form of Test Pieces. — For tensile tests, the form of test 
pieces shown In Fig. 3, page 43, shall be used. 

For compressive tests, 2-in. cubes shall be used. 

9. Mixing and Moulding. — The material shall be weighed, 
placed on a non-absorbent surface, thoroughly mixed dry if sand 
be used, and a crater formed in the center, into which the proper 
percentage of clean water shall be poured ; the material on the outer 
edge shall be turned Into the center by the aid of a trowel. As soon 
as the water has been absorbed, the operation of mixing shall be 
completed by vigorously kneading with the hands for one minute. 

Immediately after mixing, the paste or mortar shall be placed In 
the mould (Figs. 4 and 5, page 44) with the hands, pressed In firmly 
with the fingers, and smoothed off with a trowel without ramming. 



* This sand may now (1912) be obtained from the Ottawa Silica Co., at a cost 
of two cents per pound, f . o. b. cars, Ottawa, 111. 

55 



METHODS FOR TESTING CEMENT 

The material shall be heaped above the mould, and, in smoothing 
off, the trowel shall be drawn over the mould in such a manner as 
to exert a moderate pressure on the material ; the mould shall then 
be turned over and the operation of heaping and smoothing off 
repeated. 

The temperature of the room and of the mixing water shall be 
maintained as nearly as practicable at 21° cent. (70° Fahr.). 

10. Storage of the Test Pieces. — During the first 24 hours after 
moulding, the test pieces shall be stored in a moist closet. This 
consists of a box of soapstone or slate, or of wood lined with metal, 
the interior surface being covered with felt or broad wicking kept 
wet, the bottom of the box being kept covered with water. The 
interior of the box is provided with glass shelves on which to place 
the test pieces, the shelves being so arranged that they may be 
withdrawn readily. 

Test pieces from any sample which vary more than 3% in 
weight from the average, after removal from the moist closet, shall 
not be considered in determining strength. 

After 24 hours in the moist closet, the pieces to be tested after 
longer periods shall be immersed in water in storage tanks or pans 
made of non-corrodible material. 

The air and water in the moist closet and the water in the 
storage tanks shall be maintained, as nearly as practicable, at 21° 
cent. (70° Fahr.). 

11. Tests of Tensile Strength. The tests may be made with 
any standard machine. 

The clip is shown in Fig. 6, page 46. It must be made accu- 
rately, the pins and rollers turned, and the rollers bored slightly 
larger than the pins so as to turn easily. There should be a slight 
clearance at each end of the roller, and the pins should be kept 
properly lubricated and free from grit. The clips shall be used 
without cushioning at the points of contact. 

The test pieces shall be broken as soon as they are removed from 
the water. The load shall be applied at the rate of 600 lbs. per 
minute. 

Test pieces which do not break within % in. of the center, or 
are otherwise manifestly faulty, shall be excluded in determining 
average results. 

12. Tests of Compressive Strength. — The tests may be made 
with any machine provided with means for so applying the load 
that the line of pressure is along the axis of the test piece. A ball- 
bearing block for this purpose is shown in Fig. 7, page 48. 

56 



METHODS FOR TESTING CEMENT 

The test pieces as soon as they are removed from the water shall 
be placed in the testing machine, with a piece of heavy blotting 
paper on each of the crushing faces, which should be those that 
were in contact with the mould. 

13. Constancy of Volume. — The tests of constancy of volume 
comprise ''normal tests," which are made in air or water, main- 
tained as nearly as practicable at 21° cent. (70° Fahr.), and the 
"accelerated test," which is made in steam. These tests shall be 
made in the following manner: 

Pats about 3 in. in diameter, y^ in. thick at the center, and 
tapering to a thin edge, shall be made on clean glass plates (about 
4 in. square) from cement paste of normal consistency, and stored 
in a moist closet for 24 hours. 

Normal Tests. — After 24 hours in the moist closet, a pat is im- 
mersed in water and observed at intervals. A similar pat, after 24 
hours in the moist closet, is exposed to the air for 28 days or more 
and observed at intervals. The air and water are maintained, as 
nearly as practicable, at 21° cent. (70° Fahr.). 

Accelerated Test. — ^After 24 hours in the moist closet, a pat is 
placed in an atmosphere of steam, upon a wire screen i in. above 
boiling water, for 5 hours, the apparatus being such that the steam 
will escape freely and atmospheric pressure be maintained. The 
apparatus is shown in Fig. 8, page 49. 

The cement passes these tests when the pats remain firm and 
hard, with no sign of cracking, distortion, or disintegration. 



57 



CHEMICAL ANALYSES 

Reprint of Report Authorized by the Committee 

NEW YORK SECTION SOCIETY FOR CHEMICAL INDUSTRY 

Method Suggested for the Analysis of Limestones, Raw 

Mixtures and Portland Cements by the Committee 

ON Uniformity in Technical Analysis with 

THE Advice of W. F. Hillebrand 

Solution. — One-half gram of the finely powdered substance is 
to be weighed out, and, if a limestone or unburned mixture, strongly 
ignited in a covered platinum crucible over a strong blast for 15 
minutes, or longer if the blast is not powerful enough to effect com- 
plete conversion to a cement in this time. It is then transferred 
to an evaporating dish, preferably of platinum for the sake of 
celerity in evaporation, moistened with enough water to prevent 
lumping, and 5 to 10 c.c. of strong HCl added and digested with the 
aid of gentle heat and agitation until solution is complete. Solu- 
tion may be aided by light pressure with the flattened end of a glass 
rod.* The solution is then evaporated to dryness, as far as this 
may be possible on the bath. 

Silica (Si02) . — The residue without further heating is treated at 
first with 5 to 10 c.c. of strong HCl which is then diluted to half 
strength or less, or upon the residue may be poured at once a larger 
volume of acid of half strength. The dish is then covered and di- 
gestion allowed to go en for 10 minutes on the bath, after which the 
solution is filtered and the separated silica washed thoroughly with 
water. The filtrate is again evaporated to dryness, the residue 
without further heating taken up with acid and water and the small 
amount of silica it contains separated on another filter paper. The 
papers containing the residue are transferred wet to a weighed 
platinum crucible, dried, ignited, first over a Bunsen burner until 
the carbon of the filter is completely consumed, and finally over 
the blast for 15 minutes and checked by a further blasting for 10 

* If anything remains undecomposed it should be separated, fused with a 
little Na2C02, dissolved and added to the original solution. Of course a small 
amount of separated non-gelatinous silica is not to be mistaken for undecomposed 
matter. 

58 



CHEMICAL ANALYSES 

minutes or to constant weight. The silica, if great accuracy is 
desired, is treated in the crucible with about lo c.c. of HFl and four 
drops of H2SO4, and evaporated over a low flame to complete dry- 
ness. The small residue is finally blasted, for a minute or two, 
cooled and weighed. The difference between this weight and the 
weight previously obtained gives the amount of silica.* 

Alumina and Iron (ALOs and Fe203). — ^The filtrate, about 250 
c.c, from the second evaporation for Si02, is made alkaline with 
NH4OH after adding HCl, if need be, to insure a total of 10 to 15 
c.c. strong acid, and boiled to expel excess of NH3, or until there is 
but a faint odor of it, and the precipitate iron and aluminum hy- 
drates, after settling, are washed once by decantation and slightly 
on the filter. Setting aside the filtrate, the precipitate is dissolved 
in hot dilute HCl, the solution passing into the beaker in which the 
precipitation was made. The aluminum and iron are then re- 
precipitated by NH4OH, boiled and the second precipitate collected 
and washed on the same filter used in the first instance. The filter 
paper, with the precipitate, is then placed in a weighed platinum 
crucible, the paper burned off and the precipitate ignited and finally 
blasted 5 minutes, with care to prevent reduction, cooled and 
weighed as Al203+Fe203.t 

Iron (Fe203). — The combined iron and aluminum oxides are 
fused in a platinum crucible at a very low temperature with about 
3 to 4 grams of KHSO4, or, better, NaHS04, the melt taken up with 
so much dilute H2SO4 that there shall be no less than 5 grams ab- 
solute acid and enough water to effect solution on heating. The 
solution is then evaporated and eventually heated till acid fumes 
come off copiously. After cooling and redissolving in water the 
small amount of silica is filtered out, weighed and corrected by 
HFl and H2S04.i The filtrate is reduced by zinc, or preferably 
by hydrogen sulphide, boiling out the excess of the latter afterwards 
while passing CO2 through the flask, and titrated with permanga- 
nate.! The strength of the permanganate solution should not be 
greater than 0.0040 gr. Fe203 per c.c. 



* For ordinary control in the plant laboratory this correction may, perhaps, 
be neglected; the double evaporation never. 

t This precipitate contains Ti02, P2O5, Mn304. 

+ This correction of AI2O3 Fe203 for silica should not be made when the HFl 
correction of the main silica has been omitted, unless that silica was obtained by 
only one evaporation and filtration. After two evaporations and filtrations i 
to 2 mg. of SiO are still to be found with the AI2O3 Fe203. 

§ In this way only is the influence of titanium to be avoided and a correct 
result obtained for iron. 

59 



CHEMICAL ANALYSES 

Lime (CaO). — To the combined filtrate from the Al203+Fe203 
precipitate a few drops of NH4OH are added, and the solution 
brought to boiling. To the boiling solution 20 c.c. of a saturated 
solution of ammonium oxalate are added, and the boiling continued 
until the precipitated CaC204 assumes a well-defined granular 
form. It is then allowed to stand for 20 minutes, or until the pre- 
cipitate has settled, and then filtered and washed. The precipitate 
and filter are placed wet in a platinum crucible, and the paper 
burned ofT over a small flame of a Bunsen burner. It is then 
ignited, redissolved in HCl, and the solution made up to 100 c.c. 
with water. Ammonia is added in slight excess, and the liquid is 
boiled. If a small amount of AI2O3 separates this is filtered out, 
weighed, and the amount added to that found in the first determina- 
tion, when greater accuracy is desired. The lime is then repre- 
cipitated by ammonium oxalate, allowed to stand until settled, 
filtered and washed,* weighed as oxide by ignition and blasting in a 
covered crucible to constant weight, or determined with dilute 
standard permanganate. f 

Magnesia (MgO). — The combined filtrates from the calcium 
precipitates are acidified with HCl and concentrated on the steam 
bath to about 150 c.c, 10 c.c. of saturated solution of Na(HN4)HP04 
are added, and the solution boiled for several minutes. It is then 
removed from the flame and cooled by placing the beaker in ice 
water. After cooling, NH4OH is added drop by drop with constant 
stirring until the crystalline ammonium-magnesium orthophosphate 
begins to form, and then in moderate excess, the stirring being con- 
tinued for several minutes. It is then set aside for several hours 
in a cool atmosphere and filtered. The precipitate is redissolved 
in hot dilute HCl, the solution made up to about 100 c.c, i c.c. of a 
saturated solution of Na(NH4)HP04 added, and ammonia drop by 
drop, with constant stirring until the precipitate is again formed as 
described and the ammonia is in moderate excess. It is then al- 
lowed to stand for about 2 hours, when it is filtered on a paper or a 
Gooch crucible, ignited, cooled and weighed as Mg2P207. 

Alkalies (K2O and Na20). — For the determination of the alka- 
lies, the well-known method of Prof. J. Lawrence Smith is to be 
followed, either with or without the addition of CaCOa with 
NH4CI. 



* The volume of wash-water should not be too large; vide Hillebrand. 
t The accuracy of this method admits of criticism, but its convenience and 
rapidity demand its insertion. 

60 



CHEMICAL ANALYSES 

Anhydrous Sulphuric Acid (SO3). — One gram of the substance 
is dissolved in 15 c.c. of HCl, filtered and residue washed thor- 
oughly.* 

The solution is made up to 250 c.c. in a beaker and boiled. 
To the boiling solution 10 c.c. of a saturated solution of BaCU is 
added slowly drop by drop from a pipette and the boiling continued 
until the precipitate is well formed, or digestion on the steam bath 
may be substituted for the boiling. It is then set aside over night, 
or for a few hours, filtered, ignited and weighed as BaS04. 

Total Sulphur. — One gram of the material is weighed out in a 
large platinum crucible and fused with Na2C03 and a little KNO3 
being careful to avoid contamination from sulphur in the gases 
from source of heat. This may be done by fitting the crucible in a 
hole in an asbestos board. The melt is treated in the crucible with 
boiling water and the liquid poured into a tall narrow beaker and 
more hot water added until the mass is disintegrated. The solution 
is then filtered. The filtrate contained in a No. 4 beaker is to be 
acidulated with HCl and made up to 250 c.c. with distilled water, 
boiled, the sulphur precipitated as BaS04 and allowed to stand over 
night or for a few hours. 

Loss on Ignition. — Half a gram of cement is to be weighed out 
in a platinum crucible, placed in a hole in an asbestos board so 
that about three-fifths of the crucible projects below, and blasted 
15 minutes, preferably with an inclined flame. The loss by weight, 
which is checked by a second blasting of 5 minutes, is the loss on 
ignition. 

May, 1903: Recent investigations have shown that large errors 
in results are often due to the use of impure distilled water and re- 
agents. The analyst should, therefore, test his distilled water by 
evaporation and his reagents by appropriate tests before proceeding 
with his work. 

* Evaporation to dryness is unnecessary, unless gelatinous silica should have 
separated and should never be performed on a bath heated by gas; vide Hillebrand. 



61 



^ 



